The answer is simply a mater of logistics. Magneto is one of the main X-Men villians so even if her were to die he would be brought back from the dead by some Deus Ex Machina set up in the past, present, or future. Gentaro lives by a similar rule as a main rider. He has died once already and has ressurected thus proving a main rider won't stay dead until he has beaten his main villian. Even then you have to take cross dimensions into consideration with the **** tons of AR worlds in both their galaxies. Even if one set dies their are billions of others out there with different results. Thus my vote is they both live becuase that is just how fandoms work. Cheers bitches.