Lol Magic Kingdom will be able to... but DHS certainly won't. If there's only 8-9 attractions open during its overhaul while Universal opens up E-ticket after E-ticket, attendance could plummet to 8.5-9 million. AK will hold steady due to Avatar. Epcot is a wildcard - it could hold well until Frozen or not.
But from what the insiders have hinted, Comcast management has just fasttracked several attractions and numerous upgrades/enhancements to exisiting attractions for 2016/2017, in addition to Kong, CityWalk 3.0, Sapphire Falls and the waterpark. So Avatar could also be competing with Star Trek, Fast & Furious, an Soarin' esque E ticket to replace Twister, the Jurassic World revamp for JP, possibly something Marvel or a LC revamp. The folks here and at OU seem exciting about what Universal has up its sleeve.
Universal doesn't announce attractions... it builds them