No. That's a stupid idea for desktop. Not everyone needs 64GB of RAM, but some of us do - and that would be an expensive and awful upgrade to have to throw out your CPU with 32GB RAM on-chip just to put in the same CPU with 64GB on-chip. It makes absolutely no sense.
So you're talking about taking a $300 CPU chip and turning into a $500 or $800 chip depending on how much RAM is on the SOC. But the fact still remains that the vast majority of the RAM sits idle while the CPU processes through relatively small chunks of it at a time, which is what cache is for. If anything I'd rather see more cache RAM on the CPU itself than having to pay for a CPU + RAM on the same SOC. The performance gain from combining CPU + RAM on the same "SOC" is not that great enough to warrant doing that as an approach for all computers - Apple is doing this mostly because it saves them money. There's a lot of push back from power users about expandability not even being an option anymore. But 99% of Apple's customer base doesn't have any need for expandability or power-user features, or having the fastest silicon available because they only use it for facebook, facetime, or a few other basic applications. And that's fine. I won't be buying one though.