As someone who primaries on Xbox, the answer is obviously "no." Xbox Game Studios could go third-party tomorrow and it wouldn't matter much for MS's financials in the long run.
That being said, I'd prefer they didn't. I like their hardware, I vastly prefer their controllers (though the DualSense is Sony's best controller to date), and I think that competition is good for the industry.
Sony losing massive amounts of market share with the PS3, including getting trounced by the 360 in the U.S., caused Sony to make a system that was more affordable for players and easier to develop for.
The PS4's initial reception combined with MS making serious mistakes regarding used games, mandatory online, and forced Kinect caused the pendulum to swing back in Sony's favor, though not quite as hard, and as a result MS quickly abandoned their most controversial plans.
Now here in Gen 9, the only big mess-up either Sony or MS has made is the latter mistakenly thinking that producing more units of the Series S than of the Series X was a good move because it was cheaper and therefore a lower barrier to entry, when in reality it's become clear that in a "you get what you pay for" scenario, people will willingly pay more for the premium SKU.
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In accordance to the VGC forum rules, §8.5, I hereby exercise my right to demand to be left alone regarding the subject of the effects of the pandemic on video game sales (i.e., "COVID bump").