It is out of beta testing phase and the marketplace will have over 250 collections. https://nftnow.com/news/kraken-nft-marketplace-launches-supports-250-nft-collections/
That's certainly good news. But it's not a guarantee MATIC will be made legal tender in the long run. I highly doubt a nation-state will do this, especially when Polygon/MATIC is not as reliable as Bitcoin is. The OP is very optimistic with Polygon, probably because he/she is heavily invested in it. Either MATIC becomes a national currency in the future, or it remains just the way it is.
What's important is that Polygon stays decentralized so that it could stand the test of time. There are so many competing chains on the market, but only one can be the winner. Who knows what the future will bring to Polygon and the whole crypto/Blockchain industry? Just my opinion