Speaking purely out of theory here since that's the best I usually can do- with the changes to Infiltrator and certain attacks being able to go through Substitute in general, I think Baton Pass is less overwhelming than it used to be; I took a look at Slant's RMT and he does list some clear counters, 3/4 of which aren't particularly situational I don't think (although Haze is still debatable), and you brought up Heatran which inherently has the ability to completely wall Talonflame (admittedly might be dropping in usage already, idk)... On the topic of Heatran, actually, is Torment blocked by Substitute, and does the effect stay through Baton Pass? I think it would slow down boosting considerably if it's used early enough... Of course, that's the 4th gen in me speaking, and I'm not sure how usable that set is now. Perhaps Mold Breaker Taunt from Haxorus or Mega Gyarados? From what I heard from Roo Kyurem-B is a relatively high-viability threat as well, and as far as I know it's basically destroyer of stall. Again, though, this is all mostly theory since I don't play much myself, much less against Baton Pass. I guess in the end it still comes down to "do you have x counter to baton pass because if not you lose."
As for Swagger I'm fine with that going (and in fact I expected a topic about it (and Blaziken) sooner) although maybe a little more specifically; perhaps Prankster+Swagger or Swagger+Foul Play or all three together? I know how much everyone loves that whole Swagplay thing (lookin' at you, Xiph) so mmmmmmmaybe Swagger alone can stay or something idk. After the evasion ordeal I do agree that anything this luck-based is probably not a good thing to keep around, regardless of the equal chance of it backfiring on the user, considering nothing with Own Tempo is particularly usable aside from Slowbro/king, both of which would much rather have Regenerator. It's interesting how this is a thing now, though, when nobody batted an eye at Liepard in 5th gen. I guess Klefki's better typing made it more obvious.
I talk a lot for how non-competitive I usually am, sorry >>