I want to start a Muppet Wiki page for this, but I'm not sure how to source it. The only source I've seen is from Tough Pigs' Facebook and forum posts. Tough Pigs has not yet posted an article about them (I think it was said that Tough Pigs will hold off on Muppet Toy Fair coverage until next week).
I think it was said on the Tough Pigs forum that they were told that the Mini Mates is currently only planning the ones announced (though I think they're considering more) but that there are plans for more "Muppet Selects".
And here's my wishlist/speculation for more series:
Speculation for who will be paired with who in series 1: Kermit and Robin, Miss Piggy and Scooter, Fozzie and The Swedish Chef, Gonzo and Camilla, Bunsen and Beaker.
Series 2 wishlist: Dr. Teeth and Animal, Floyd and Janice, Zoot and Lips, Rowlf and Baskerville, Statler and Waldorf.
Series 3 wishlist: First Mate Piggy and Link Hogthrob, Dr. Strangepork and Mahna Mahna, Snowths 2-pack (there could be a Mahna Mahna and Snowth 2-pack, but then we'd either be missing a Snowth or have to have two Mahna Mahnas in order to have two Snowths), Penguin 2-pack, Walter and Uncle Deadly.
Muppet Selects Speculation: Miss Piggy and Gonzo, Animal and Rowlf, Bunsen and Beaker.