The Avengers: Age of Ultron ****Now with Spoilers in living Technicolor***

Nope to both of those. They will not be the children of Magneto nor will they be mutants as Fox has the rights to those elements and will never play nice with Marvel. Rumor has it that Marvel is going to position the Inhumans (given powers via the Terrigen Mists) to be the MCU equivalent of mutants, but mutants proper are off limits for them until Disney writes Fox a big *** check or Fox goes 7 years without an X-Men property in active development, in which case the rights revert to Marvel/Disney.

In either case, it's unlikely until after 2016...

X-Men: Apocalypse (2016) May of 2016 release date. In pre-production now.

So, 2023? Probably too late for Marvel by then.