Looking around, I've only found phase change as being anywhere close, being available in sampling quantities from two companies. Assuming it's reliable and fast enough, then it's a matter of scaling. It takes a lot to replace flash production. I don't expect two companies to displace flash in just a few years, even being as well-backed as they are.
It depends upon where the technology is implemented. Plus hybrid systems would likely exist first.
There are other technologies out there in limited production. The problem is nothing has the potential of the phase change technologies.
The question then becomes how quickly can phase change reach or surpass flash density. Hopefully at a lower cost.