I think Hot Toys can always be around, IF they keep up with the times and don't get stuck in a rut. I'm not necessarily saying they are in one now, per se; while I hate all the Iron Man variants as much as some people do, you always need to be looking into new opportunities and keeping an eye on the market and what's trending. I also agree that some older properties with long-term fanbases need some love. Star Wars is a GREAT step forward (although I think their rapid release schedule is going to hurt them - I decided to bail on the line pretty quickly when I saw that there were 7 must-have figures all coming up at almost the same time). If anyone is interested in a MIB exclusive Han/Chewie set at retail, shipped as soon as I get it from Sideshow, let me know.
It's been alluded to already in this thread, but for me and my Hot Toys collection, I'm not overly concerned with making a big profit, but I also don't want my figures to be worthless, either. The question, I think, is how many of their currently-popular properties will stand the test of time. Will Iron Man always be popular? Maybe, though not as much as it is now. Will the Robert Downey, Jr. Iron Man movies always be popular? Ah...that's a better question that I'm not sure is true. Am I going to enjoy these figures as much when the property has died down? I dunno.
That's why, as someone said, don't collect just to finish a set or for a profit down the road. Collect because you really enjoy the property, and then you won't concern yourself with what happens later.
Will I always be collecting? No, I'm sure I won't. I'm sure kids, family, life, finances will get in the way at one point or another, either temporarily or not. And I'm not sure if I'll be keeping all those Hot Toys when it does. I will keep my Bonds. I'll keep my Star Trek. But the Marvel/DC/etc? That's yet to be seen.