@tatel Thank you again for the great set of questions. They come at a good time, and address a conversation going on elsewhere that talks about this issue.
In particular, a lot of the folks who volunteer time on the forums get weary of answering questions from people who try to install OpenWrt on underpowered devices, then ask for help. It's hard to say, again and again, "No way ... Sorry" for people whose technical skills aren't up to making it work.
We were looking for some way to help newcomers avoid a purchase they'll regret, while remaining friendly and supportive to all who use OpenWrt.
Our conclusion was to note the difference between support (getting help) and suitability (how easy/hard it is to install OpenWrt on a particular device.) We've put up a draft page https://openwrt.org/playground/richb/support-suitability to explain our thinking.
On to your questions:
1- Yes, please do it, as long as possible, and please make a (very) clear statement about it. Perhaps it would be easier to make a statement addressed to those (few, I guess) of us that are used to build our own images, that to explain all possible cases to a newcomer who wants to download some cool firmware.
Our policy is that all OpenWrt devices (even old hardware or releases) get support. That is, you can read the docs, go to the forum and ask questions, etc. There will be more people who know about and can answer questions about newer stuff, but all (polite) questions are welcome.
2- Please consider it is still possible to buy new 4/32 hardware. I actually bought four TP-Link WR940N v6.0 last November and I could buy right now some 800 at my usual store. It is an ath79 4/32 device. I think it would be a little bit shocking if a free software distro could not be deployed on new hardware.
The page above talks about how easy/hard it is to install the current OpenWrt with three tiers: Recommended, Limited, and Difficult.
A 4/32 device will be considered Difficult, since you need to know a lot to get OpenWrt installed. That doesn't mean it won't work, or that you'll be unhappy, just that it'll be harder to install than on other devices.
3- Please consider that price and features are not always the motive to buy some hardware. I bought those 4/32, ath79 WR940Ns because WR841N v13, which is an 8/64 ramips device, and is 25% cheaper (15 vs 20 € ) has bad wifi.
I knew for sure that ath79 is rock-solid because all our devices (remember, some 50) are ath79 and last year they gave 0 incidences, even if most of them are close to be 7 year-old.
These three tiers make no judgement about quality, price performance, reliability, or additional features of routers. They only discuss how easy or hard it will be to get started with OpenWrt.
I want them rock-solid and long-lasting because if one of them fails, it could be that I need to drive some kilometers off road to reach the farm where it is deployed, and that is not cheap, neither in time nor money. So I got the WR940Ns, because, in the long run, they cost the less, even if they are 4/32, even if they cost 25% more, even if there are (seemingly) "better deals". Remember, out organization is a not-for-profit.
This would not be a change in your ability to continue to using these devices. You've already learned the technical skills to install OpenWrt. If we state that "it's difficult", it simply warns newcomers that there are easier devices.
4- Please consider, before you say that would give so much more for that 20 €, that before buying those WR841N v13s I checked the forum, I saw the concerns about wifi stability and then I saw somebody stating boldly it worked perfectly for him.
Don't get me wrong, I gratefully take your advice about hardware, there could not be better advice, but I always will be cautious and always, when buying new models, at first time, will purchase just a few ones to test them myself.
As I understand your situation, you are doing exactly the right thing. You support a large number of people (fifty? more?) There is real value in making sure everyone's hardware is similar, just to decrease your support load. And you have the incentive to spend the time to keep your customer's OpenWrt builds up to date.
Perhaps looking for devices that are rock-solid and last more than 6 years (which is quite the double that my LED TV did) is to ask too much, but I don't think so, since it is exactly that those ath79 devices are still doing, while here it does look (sometimes) as if they should be dumped from "day cero".
5- Please don't assume there is any "typical use case" Simply assume there will always be a use case for that "pesky" hardware. While we could look for high throughput in our PtP links, don't look for more that 30 mbps on our PtMP links. So ath79 is still good for us, and I guess it is good for those tens of thousands of freifunk guys, too.
Freifunk has the same problem as you - but multiplied 100-fold. They have a big incentive to continue making builds that fit their needs. OpenWrt, and the ability to use it on older devices, is not going away. We are just providing advice to new people about how easy/hard it will be to try OpenWrt.
6- AFAIK, what OEMs as TP-Link do, is to put an older kernel, etc, in their firmwares. If they can, I can't understand why OpenWrt community could not. It would be a shame to have to get OEM firmware again, and it does look as it being possible, not just for 4/32 devices, but for 8/64 too, in a not-so-far future.
You'll never see me defend vendor firmware. In fact, I believe that, Friends don't let friends run vendor firmware.
While I think it could be too late for 4/32, I think something should be done so 8/64 devices can be supported long after they vanished from stores, as it should be with free software. I can only assume this a a matter of interest (or lack of). So if OpenWrt community thinks monetary support is needed, it is legitimate to say it clearly. Perhaps we could open a new thread about this matter.
That's a separate thread. I don't get the sense that people feel the need for compensation to provide support for OpenWrt - just an end to the frustration of newcomers who try and fail to install OpenWrt on an underpowered device that "looked OK" in the Table of Hardware.
7- I don't think, in any way, that devices that are perfect for the work, known for being rock-solid, long-lasting and can be purchased new right now, should get dumped. I hope that openwrt community does think the same. If this is not the case, or if there is danger this can not be done, or if there is widespread consense that it is not worth, please make a statement so we can start to look for alternatives.
I hope you can see that our new advice (Recommended/Limited/Difficult) mostly benefits newcomers. Experienced and knowledgeable people like you can continue to use OpenWrt as you always have. Thanks for these great questions.