Well yeah even though I do not think time is THAT much of a major factor for it to be a good game like so many make it out to be (imo 3 or maybe 4 years would be ideal for a game like DMC, not too little for them to make new assets and not too long for them to risk to lose focus and water the game down), I still have to give the guy reason. Helps that his tone was actually calm and reasonable instead of sounding like a spiteful dog like we see here on the boards all the time, which helps his credibility as a fan.
With that said, if they release a teaser in 2016, what's the big deal (since Vash said he would be disappointed if that was the case). If they don't do something major, like a full fledged trailer, but just a teaser like that one with creepy ass Dante for DMC4, or even that one only showing the witcher medallion for Witcher 3, that would mean the game is in its very early production stages and would not see the light supposedly till another few years.
Also, I read one of the video's comments saying that DMC4 would have probably turned out great if its dev process wasn't so troubled, with mid-process decisions regarding story and gameplay resulting in the constant changing of the game. That's what he says, and I gotta say I think he's got a point, which goes back to my opinion that time is not necessarily the main deciding factor for the game to be good or not.