Well, I'm no expert but UU is my most played tier and some of those mons won't survive in UU imo. I'll start with the UU pokemon you think will drop. Politoed and Ninetails will be very interesting. On one hand, both are outclassed in stats and moves by the plethora of fire and water types in UU (chandelure, darmanitan, suicune, slowbro), but if weather teams continue to see play they could become very powerful and even possibly go to BL (remember vulpix lol). Toxicroak is in a similar boat, UU is FULL of fighting types (heracross, mienshao), but if weather becomes big he could become a huge threat. Tentacruel will almost certainly drop imo. Starmie would be a fearful sight in UU, I'm not sure it will get there but if it does I would hope for a suspect and BL ban very quickly. Breloom I agree with, but people are still using it, so it will stay OU for a while. In edition, I'd like to propose hydreigon as a new UU threat. Fairies make it's life hell, and it's been UU before (though holy shit is was scary there).
The new pokemon that I can see being a threat in UU for a while are malamar, diggersby, florges, sylveon, tyrantrum, noivern, heliolisk and gourgeist. It is likely that a couple of them will drop down to RU later. Imo noivern and sylveon will both really excel in UU and will be the biggest new threats, but who knows what will happen.
Furfrou, Delephox, Clawtizer, Avalugg and Barbaracle will all probably drop to RU or even NU. There is no way those things will stay UU imo. Doublade is overhyped also, it's special defence is pityful, it has a useless ability for its moveset and just fails to stand out imo. Maybe as a physical wall it will find a niche, but not enough to stay UU.