This doesn't have to do with Hawlucha in particular, but I am really excited about September's tier shift.
Diancie will obviously drop, and I think it will fit decently in the tier. It will be the best possible answer to Honchkrow (unless it starts running Steel Wing, which it doesn't have much room for) and also deals with Fire types in general (though it fears certain coverage moves like Energy Ball on Mix/SpecialTini and Chandelure and EQ on Darm) as well as Crobat and Mega Absol without Iron Tail (used for Florges). However, Diancie's many weaknesses and lack of recovery will probably discourage it from seeing much use since most Pokemon in the tier have a common way to hurt it and things like Jirachi, Aggron, Blastoise and Swampert are great answers to it that are common in the tier. Even Hydreigon is dangerous to it because of Earth Power, Surf and Iron Tail. I think its offensive Rock Polish LO set will honestly be its best bet in the tier, as long as Bullet Punch Metagross and Lucario don't get in its way.
Togekiss looks like it will drop along with it, discouraging Dragon/Ground coverage and bringing another solid answer to Hydreigon and, to an extent, Mega Blastoise if specially defensive. Scolipede will also qualify for a retest if its usage stays where it is.
As for Pokemon rising, Slowbro, Heracross and Raikou seem to be the most likely candidates and Mew, Starmie, Sableye and Amoonguss have a really good chance as well. With Slowbro gone, Alomomola will likely replace it as the physical Water wall of the tier (and hopefully get that thing out of RU!), though it won't be able to fully replace it since it has little offensive presence and the only role they share is as a physically bulky Water wall. Sableye and Starmie aren't super-common in July's OU stats, but they have been seeing a lot of usage in OU since Aegislash's ban as a spinblocker and spinner so they could rise.
Sorry if I end up contributing to a negative discussion. I just can't wait to speculate.