Can't it be simply that he is trying new things? Kojima always re-defined MGS with every single game, and (almost) always good things came out of it. When You think about it, MGS2 on paper seemed like a totally crazy, bonkers idea, if one would compare it to MGS1. What Kojima achieved and strived for in Wings of Liberty, was nothing like what one would expect from a standard, cookie-cutter sequel to a game like MGS 1. Even Snake Eater was completely different in tone. We may look back at the MGS series as some continuous saga, but every single entry in the franchise was a small revolution in iteself. And Kojima always treated each game as a separate experiment.
And in V he is back to experimenting, looking like he's full of ideas and more passionate about the game, than any other MGS related title since... Snake Eater I think. Dividing the fanbase into some "old guard vs newbs" camp is a bit silly and premature. Firstly becose we don't know enough about V to say that the story won't serve the franchise, so far the only foreboding tidbit of information is that Hayter won't be returning, and even that could serve the game for the better, if the new guy will be up to the task. And secondly becouse it's exactly this kind of re-defining the status quo by Kojima, that made all the previous games so good. In fact, I would argue that the true "older fans" that You talk about, should recognise the fact that what Kojima is doing with V is exactly the sort of thing he's been doing with all MGS games for the past few decades, and that's always a reason to be excited.
Also there is nothing about V that shows signs of catering to a newer, younger demographic.