I think the new sockets should be planned so that AM5 is 4x DDR4 and there can be AM5+ DDR4+DDR5 CPUs compatible with both AM5 and AM6.
There could even be hybrid AM5+ motherboards like in the past where half the slots are DDR4 and the other half are DDR5 allowing only one SO-DIMM per channel but compatible with AM5, AM5+, and AM6 CPUs. Being able to mix a total of 4 sticks of DDR4 and DDR5 would be an added bonus.
1. I built a system with an AM2+ mobo, AM2+ Phenom X3, 2x DDR2.
2. I added 2x DDR2
3. Upgraded to AM3 Phenom II X6
4. AM2+ mobo died
5. I could have bought a hybrid AM3 mobo and keep the DDR2, but that meant only 2 usable slots. So I bought an AM3+ board, 2x DDR3, and a GT 720 (sucked, I wanted an R7 260).
6. Replaced the DVD burner with a BD burner.
7. AM3+ mobo died. Repaired.
8. Replaced the system HD with a 2.5" SSD.
9. Replaced the 2000-era case with a USB 3.0 case.
10. SSD crawl. Refresh.
11. Replaced the 2.5" SSD with an old SATA M.2 and the GT 720 with an ex-eGPU RX 460 (fiddled with). 2.5" went to a laptop.
12. Upgraded the cooler and added fans.
13. Upgraded the PSU, bought an AM2+ mobo and case, and reused the X3, DDR2, GT 720, DVD burner, old PSU, and an SSHD to build a new system.
14. RX 460 died. Temporarily replaced with a new GT 710 (sucks).
15. I could upgrade the AM3+ system with an 8-core AM3+ FX and move the X6 back to the AM2+.
16. Replace the AM3+ system internals with Zen and move them to the AM2+ system.
I was disappointed that FX had half the FPUs per core than K10.
I was disappointed that you could not put an AM4 CPU on an AM3+ board with DDR3.
I am now disappointed that one cannot find 8-core FX with Wraith at retailers anymore (I would put the Wraith on the AM2+ system).
I saw an interesting FX deal quite a while ago, but it was not Wraith. Something much better came up later when I was not looking.
A new 8-core FX with Wraith should not cost more than Ryzen 1200.