That would be a neat feature. Group mails would also be a great addition to the game (I mean, sure studio mail, but it would be nice to be able to send a message with several recipients, much like an ordinary email). That would be good in case you need to send the same message to several people without copying and pasting and getting all messy. Indeed, if group emails would be implemented, that would perhaps be a way of having something like an inter-studio chat if all the people can see each other's messages.
At the very least, it would be great to have some way of creating separate studio chat channels (in case some studio members want to, say, get their kinks on without making the rest of us feel awkward). Chat rooms across studios might be trickier, but there should be some way of having chat rooms within studio chat at least, much like the present producer channel but say, chat1, chat2, chat3, or so following the same functions that already exist.
As usual, I should say that I am basically computer illiterate, and I have no clue if that would take thousands of hours of work to implement or be a matter of someone just doing a bit of lazy work on a Tuesday afternoon. The group message function might be a simple "chat room"-esque way of allowing better communication between players outside of studio chat.