Oh.
…I dunno what to tell you, then.
If you’re on a 5800X3D, AM5 is terrible upgrade value now. If you wait for DDR5 prices to come down, it will indeed be a “dead end platform” when you buy, as I don’t think AMD will release AM6 unless it’s DDR6.
If you do workstation stuff, get DDR4 threadripper (or even a fire sale EPYC server), and re-use half your RAM, but other than that I have no good advice.