They could make it work, we see 520s running well on it. And you do get windows 10 as promised, just won't get redstone or anything else. So technically it extends the lifespan of your device for a bit there. A device that is already old. This was planned in a way. New features will be coming in Redstone. Old devices will not be able to use them anyways. Why go through all the issues this could cause when instead you can drop them and not have to worry about constantly updating code for extremely old devices when windows 10 is meant for the future.
And here's the kicker. MS already knew how much percentage will drop. They still took the risk because Redstone is far too big to care about that percentage. It's a completely new market for new people to jump in on. Not even steal market share from competitors but build a new category that will be part of future market share reports. Just like they did with the surface line. The re-invention is not hardware, it's software. They don't do hardware. They just show off their own hardware they make but would prefer OEMs to do the brunt work. And that's how it is in the PC industry. This is how the 2-in-1 laptops are selling and that's how the 2-in-1 phones will be selling. And the market share will be up for grabs for any OEMs. MS isn't trying to steal that share. So they don't care if the phone shares get obliterated. They are just phones...
And I should mention. The software is designed to adapt to any hardware. The feature set that they include is what will open up OEMs to any sort of devices they wish. They don't even have to be phones, they can be ar units, video game consoles. Anything.
MS is essentially introducing a new battleground for OEMs to gain market share in.