The M61 is a gun. The Belgians are still in on the NATO weapon program with dual-keyed B61s, which are being upgraded into the dial-a-yield, JDAM-tailkit-equipped B61-12. Integrating the weapon on to Typhoon or Rafale is technically possible because both are MIL-STD-1760 compliant. (The precedent is that German and Italian Tornados carry B61s.) The question is whether the US will be cooperative, or whether it will use the nuclear arrangement as a lever to sell F-35 in Belgium and Germany.
There are about 150 B61s in Europe, including 50 at Incirlik AB that are US-only, although aircraft would have to be deployed there to deliver them. The weapons in Italy, Germany, Belgium and the Netherlands are held under an arrangement where the US can keep the weapons on European soil, as long as the hosts have a role in their delivery.
I don't think the strategic rationale for this element of the nuclear force has been deeply studied in recent years.