@shantini You've got a zillion responses, so I expect you won't read this one (and that's fair!), but for the sake of saying it:
What I have read so far is that Masto users will essentially be able to peer over the fence in to Threads at selected "famous people" accounts, but if we wanted to interact with them, we'd have to join Threads.
This is not what "interoperability" means, as far as I can tell. That's my issue. IMO. FWIW. YMMV. BBQ.
@OrionKidder that is temporary. They're testing the waters and Mosseri said this is gonna take a few months until it's fully federated without needing threads accounts.