Originally posted by Latcady:

This got discussed in another thread that might be useful for you - https://steamcommunity.com/app/892970/discussions/0/4263206669447091427/

Essentially no one knows for 100% sure, not even the devs. Ideally they want to avoid forcing people to start new maps because they know people are investing a lot of time into their worlds, but it may be unavoidable based on a few factors.

So, if you're able to accept the gamble, go for it! Otherwise if you'd rather play it safe hold off till H&H is out in a wee while.

Hope that helps :)