This paper describes "eruptible magma" to be at least 50% melted. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JB02... (with silicic magma in granite, so at least vaguely the same situation as Yellowstone). Recent observations show that the Yellowstone magma chamber is like 10% melted, maybe almost 30% in some places. https://www.usgs.gov/observatories/yvo/news/new-views-how-ma... That's not enough.

From the first link, again:

> These recent studies demonstrated for example, that silicic supereruptions with volume exceeding 1,000 km3 of eruptible magma can be generated in less than 5,000–10,000 years (which we call “Yellowstone” type), to longer than 500,000 years

And geology is not a context where "less than 5,000" realistically includes, like 5, or even 100.