I've been using 123D Beta 9 for quite some time now and I really like it. But at some point B9 will go away in favor of 123D Design. That said the forum moderators over there are pushing B9 users toward adopting Inventor Fusion. I have no problem with this - the programs behave similarly, with a few quirks that I'll have to get used to. My biggest issue is that the technology preview expires in a few months. I like some of the advantages that IF has over B9, but why does it have to go away for windows users? Why doesn't the mac version expire? Is it because mac people are better and *deserve* free software? I don't get that.
So to sum up. What happens after April for windows users? Does the rug get pulled out from under them?