I hate to ever do this but look at go to youtube and look at Halo5Followers videos or "Halo Updates(or FWM as he is known in the affiliates of the site). Their videos showcase a lot more proof then "ilovebees". I don't remember exactly which video but if you care enough about why so many people believe it is happening then please view the videos(it will be the ones with H2A in the title or something, FWM did a great video on it specifically)
BZ1 is referencing those sources not just ilovebees(but all of them relate to ilovebees and seeing as the website was recently updated not that long ago. And put in charge of a new company if my memory of the video serves me correctly)
Also if there was no H2A this year 343i would have at least hinted towards it not happening. I am still extremely skeptical and I much prefer Halo 5 if I had to choose(mostly because I need to know what happens in the singleplayer, Halo: Escalation isn't providing enough comfort)