The PLA will be stronger in absolute and relative terms to better dissuade and even fight off foreign military involvement in the future yes, but the costs to China of fighting off the US in 10 years time is still going be to orders of magnitudes more than just fighting Taiwan tomorrow. In addition to the significantly less likelihood of direct US military involvement in a Taiwan takeover under the scenario described, there will almost certainly be far less economic fallout as neither the US or EU could afford to impose economic sanctions on China if they are relying on the good graces of Beijing to supply them with COVID19 vaccines.
I usually agree with what you write, but I have to disagree vehemently with your analysis here. COVID-19 is indeed a freak, once-in-a-century event, but it's not geopolitically usable in the sense you think. The obvious objection is this: what happens once the vaccines are delivered? The West would just defer its retaliation to China invading Taiwan until after the COVID crisis passes. There's no way to cut off all avenues of American retaliation at present and there won't be for at least a decade.
And yes, it is certain that by the middle of the century China's economy will be multiple times the size of America's and its military more than a match for it not just in the western Pacific, but around the world.