That's not the only way there will be trouble. A more likely scenario is "We've been going over the numbers. To keep our costs down, we are making the following changes to our support of open source projects..." I'd be surprised if that didn't happen in some capacity in the next five years.

Actually perhaps. If the current team continues to own and run it, it'll be around forever. But eventually they'll want to sell it, the team will change, and its goals will become more feature-oriented for the sake of grabbing more premium members. This will give it less value (due to the removal of simplicity) to the average user, so its userbase will gradually shrink until a few years later they pull the plug. It's happened to almost every web service more than a decade old.

Did you foresee what happened to SourceForge?

Five years is a long time in tech. I think it's more likely that we will see same thing happen with Sourceforge and Google Code - a better thing comes along and people move to it.

This is something which is seen over and over again. Its not that loved active services and sites get turned off, it's that the userbase moves somewhere else first.

How long have you been in the software industry? Github would be lucky to be half its current size in 5 years, if it's not entirely gone by then.

I like your crystal ball. Maybe I should use it to gamble in the stock market.

As for the rest of us, you can't possibly see or guess the future that will affect that business. Maybe they'll get sued out of existence by then? Maybe the owners will run it into the ground? We hope it will continue to exist, but we can't possibly know until then.