Don't see a chance of that happening. Even with Adamant and max Atk investment I find that Entei isn't really all that strong (more on that...), but its power comes from the difficulty of switching into it.
Entei works best as an early game 'mon, and even though I've found that he's largely incapable of netting OHKOes and sometimes even 2HKOes, he's still such a good Pokemon because he whittles down everything. Its bulk has also been a pleasant surprise, so while I'm perfectly ok with him going down relatively early, it's not always suicide mission for Entei. Also, despite needing to run four attacks for just about every set, Entei's a support Pokemon above all else.
He's a threat, just a different kind of threat than what we're normally used to seeing. You need a well constructed team to make Entei work, because whittling down opposition is meaningless if you don't have anyone to clean up the pieces; Entei isn't a good sweeper and largely not a good option if you want to break down walls. CB Entei also needs a lot of support clearing hazards because it can't do its job effectively when he's taking unnecessary damage, seeing as Entei's bulk is one of its strengths. I find that defensive cores that run Aromatherapy/Heal Bell does a fairy good job of keeping it at bay, then you just PP stall Sacred Fire and Stone Edge and he isn't that bad at all. If used properly, though, your opposition should be left with a couple burns or more and half health defensive 'mons. This is more than you can ask for out of it since this is all Mega Pinsir/Megazard X/etc need to sweep. Using it properly is easier said than done though, since you absolutely have to know what you're doing or else Entei just won't work.
I'd just like to say, though, is that all of this is incredibly wacky to me. What planet is this where the whipping boy for legendaries is now a top OU threat and Salamence is seeing UU usage because he's outclassed by Dragonite and Charizard?!! Ah well, I guess it's the same one where Kangaskhan was everyone's worst nightmare and its best counter was a 380 BST 'mon... not that all of this is a bad thing though. Maybe it's just me but the meta feels fairly balanced atm.
