Brave was a wash no matter what. While it did speak to some people, and it had a good underlying message, it seems they just dumped Mereda into the Disney princess line (that she totally doesn't fit into making it an antithesis of the movie completely). I don't see a Brave 2 any more than I see Ratatouille 2. The call isn't there commercially or merchandising wise. The story could continue in a series of comic books or something (if Marvel actually published Disney comics), but there's no call or want for a second of that.
Incredibles 2, however, is a film they should be making, once they have the right ideas. Glad it's announced and I hope they're working on a solid story. They have a lot of potential since once the Paars came out with their super powers, there was a rise in super villain activity.
As for Toy Story 4... While I do agree it's a bad idea, and they hopefully rethink it, think about this. Shrek almost had 6 movies (not counting Puss's Spinoff which was still in the cards anyway)! It wasn't until the third one's formulaic and repetitive gags turned everyone against the franchise that Dreamworks decided they just need to close the series with one more film which ended on a high note (and no farts!). Ditto with Madagascar. They threatened to make a fourth one (again, not counting the spinoff), but the third one closed the franchise nicely with the gang finally getting over the zoo. Dreamworks is all about the sequels. Lately, their original films haven't been hitting any nerves. Understandable because of high concept stuff like Rise of the Guardians (based on a not well known book series). Meanwhile, you know who's MORE about sequels than Dreamworks? Blue Sky. They made less films, sure, but considering they made 9 movies, and 4 of them were Ice Ages, 2 were Rios (and only one Robots? You kiddin' me?!). And there's clearly going to be a fifth Ice Age at some point. Pixar still doesn't look too bad.