Given the current economic conditions a budget DDR4 line makes sense.The release of new parts for AM4 is really increasing the lifespan of AM4, isn’t it?
If you take a look at the smartphone market you'll see plenty of budget devices with older hardware still going, not to mention ones meant for developing countries.
Heck, Mediatek was not taken seriously until a few years ago but it still sold truckloads of SOCs, watch UNISOC do the same in the next few years.
Moore's Law is definitely slowing down and what was high end 10 years ago is still passable so to some extent the top DDR3 hardware with some tweaks would still be good for entry level, while top DDR4 with some optimization will be decent for the next 5 years IMHO.
A 6nm 5850X3D with just +5% performance over the 5800X3D would be able to keep up with a 14700k in gaming at a very competitive price, basically taking away Intel's DDR4 advantage, outside of high end oriented circles like this forum it would be a killer if it would cost 20% less than a 7800X3D based platform for not that much less performance.