No one here knows for sure what's going on, but there's lots of speculation. I think you're right about charlie's ip running out being the main cause of the closure, and it is very likely to be rethemed/removed in the next few years.
The general speculation on hex is that it was having issues parking last year, and many effects had broken over the years. It also utilises parts of the towers themselves, which will need renovations even so often. We assume that hex will reopen either late this season or for the start of next season, and that it has been closed to fix the parking issues and refurbish the ride and building. Don't worry, I doubt it's going anywhere anytime soon.