If OpenAI takes a good chunk of Google's ad revenues then it doesn't seem that fanciful that it'll be up toward the top of market caps.
[0] https://companiesmarketcap.com/alphabet-google/marketcap/ [1] https://www.statista.com/statistics/266206/googles-annual-gl... [2] https://businessplus.ie/news/most-valuable-companies/