It's a funny Tweet, but Rails is much, much bigger than Basecamp now. There's enough money invested in the Rails ecosystem at enough large and medium sized companies that Basecamp could go away entirely and Rails would continue to persist.

(I realize that there's always the possibility that this post could age like milk, and everyone might be pointing at laughing at me in 5 years. But that's also pretty much true for any piece of technology, and not unique to Rails' current situation.)