Hopefully, but it doesn't look like it, since they have specifically specified that there are 4 characters.
Diddy, Funky and Pauline is possibly the best trio of characters they could add, so great.
But Peachette is... well... I think objectively the worst option in Mario Kart Tour. It's a transformation of Toadette (like tanooki or golden mario) but with Peach's appearance. They are going to put together some variations of characters (Villager, Inklings, Tanooki, etc) to make room for a """skin""" of Peach in the selection screen. Very very weird.
Also, im fine with Daisy circuit, but I hope we keep getting Rainbow Road. And there were a couple of seconds when Pauline was announced where I really thought they added a whole row of Tour characters lol.