The developer for A310 is IniBuilds. They’re also the ones doing the upcoming (payware) Antonov An-225.
I agree that a “better fidelity” Boeing should be added to the sim. It problably SHOULDN’T be the 787-10 since that is a Premium Deluxe-only version of the plane. I’d be happy as heck if MSobo hired PMDG to take their model and build up the systems and flight model to make the Premium Deluxe worth buying, but doing that for the default 747-8 would make a deep, high-fidelity Boeing available to more people.
I would frankly be ASTOUNDED if they “bought” PMDG’s 777 to bring to the sim for free. PMDG will probably be selling those for $70 or so per variant, in line with their 737 pricing. But who knows? Microsoft has deep pockets.