What if Legion was in X-Men Days of Future Past?

So, recently I was giving an underrated X-Men show a watch which is The FX Show, Legion to which is very underrated and really good if ya haven't seen it, and then I remembered that in the comics. Legion is Professor Xavier's son and then it hit me on an idea I'm surprised was never touched upon, So I had to do some thinking and then pondered an idea, What if Legion was the main badguy in X-Men: Days of Future Past, The movie itself deals with alternate timelines and time travel, and the potential collapse of mutantkind so who better than to demonstrate that mutantkind destruction has to be none other than Legion,

Think about it, The X-Men get together with like Magneto and other mutants to try and work together to take down Legion, I would so love to see a bit of father and son chemistry between Xavier and David Haller,

And a fight between Hugh Jackman's Wolverine and Dan Stevens Legion would be so badass,