It took Skyrim around 10 years to sell 30+ million copies across every platform known to man.. God of War sold 20 million on 1 platform in its sleep...
Wrong, Skyrim sold over 30 million copies in 2016, that's 5 years after the release on Xbox 360, PS3 and PC.
In 2016 they released the Special Edition, in 2017 the NSW version and Skyrim VR.
It is most likely at 35-40 million sold copies by now, by far the best selling RPG of all time.
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PS5 is going to do fine, but yes Starfield and TES6 exclusive to Xbox (on consoles) are going to be system seller for the "Console Bethesda fans" and MS will move some units thanks to these games, but at the end of the day, they are never going to match PS5 units WW for a lot of reason. Doing better than Xbox One is a given, i mean, unless they do worse than Xbox One in both software and hardware, it's easy to achieve, but PS5 will lead by units without a lot of issues.