I can't address their expected timelines in any way, but I did want to make two points:
1. Calling any version of MC "final" is... Difficult. Or, perhaps, it doesn't quite mean what you might think it means. JRiver essentially does much of their development "in the public eye". Final, to them, means "we've moved the bulk of our development effort to the next version". That next version will, initially, be the same as this version (just like any other weekly build) except that they no longer resist (as much) making big changes that break stuff for a while.
You could look at it, a little, like "perpetually beta". Except their betas are (by and large) the most stable betas, over the long-term, that I've ever seen. I've been using MC since before it was called MC, and upgrading weekly if not daily most of that time, and... Serious problems from a new build have happened here and there, but they are incredibly rare, and can almost always be mitigated by rolling back a few builds (which itself almost always works without issue).
2. MC for Windows runs beautifully under Parallels Desktop and/or VMWare Fusion (or Boot Camp, but that's less convenient). I've been running MC in Parallels on my Macs for ages (since MC15-ish, maybe?) and I still do now with MC18, because I'm primarily a video user (or, at least, that's what I use it for the most). Buying an actual "PC" is almost certainly not necessary. Your Mac is already a PC, it just doesn't have a copy of Windows on it.