The merger plan is $2.7 billion.
Europe dominated the market in 2019 with market size of USD 22.0 billion.
https://www.grandviewresearch.com/industry-analysis/online-gambling-market
The above source claims the global market is $54.7 billion with europe having the largest online gambling market cap in the world at $22 billion. Which would mean the united states market is smaller than $22 billion.
Don't know if they can achieve an appreciable amount of penetration for US markets with $2.7 billion. The predictable move would be towards market consolidation and monopolization of some type. Similar to how coinbase and possibly paypal have been positioned to consolidate and monopolize US crypto purchasing.
I doubt this move will come with much in the way of innovation, there are already many crypto based casinos available. Legalized and deregulated gambling markets in europe and asia will likely emerge as industry frontrunners.