No, you don't need more gates in each memory cell to support each possible operation. The memory cell turns into gates. They are the same thing, just in a different configuration. And yes, it would be a ton of silicon, likely more than you're imagining. It would subsume all CPU silicon, all cache, all main memory, all mass storage. Into one fabric which at any point can either store data, or compute. And yes, it persists without power too.