If'n I knew the answer, I would answer the question LOLOLOL.
I do not know if there is a specific number of threads you can subscribe to or not. One thought that came to my mind though is that threads usually die out in time (most of them do) and you can always unsubscribe to them as new one become available that you wish to subscribe to no? I would keep going with it and if there is a maximum and you hit it...well, then you'll know
I'm sorry for being so casual hon....I really have no specific idea, but I think it's pretty unlimited or at the very least a large amount can be realized. I know that's not much help.

sabby