could this be the next GOT?

The books are good, eastern European fantasy, different from RR Martin, which is typical American writing.

However, the series doesn't look anything like the books. It seems that they've taken the names and rewritten the stories as some modern standard dark fantasy, which is the trendy now stuff now. You change 'Witcher' for 'Huntsman' and 'Ciri' for 'Snow White' and you sell the trailer as the one for 'Snow White and the Huntsman' movie.

Better read the books.

In some ways the books are better than Martin's because Sapkowski is not a sadistic asshole who enjoys crushing hopes of his fans.
There's some cool meta-humor and a touch of post-modernism (the good kind).
Got to admit that the worldbuilding is less thorough and detailed. The Continent is more generic than Westeros. In some ways CD-Project peeps made that world more alive in the games by adding new lore.
And despite the fact that the Witcher saga was one of the first true examples of gritty fantasy, it still holds on to a lot of fairy-tale traditions.

All in all, yes - it could have been the next GOT. If they had another executive producer. Someone who cares about art of television instead of forcing their ideology on other people.

If the thematic content is more engaging than people walking through corridors and dungeons with a scowl on their face.

With or without the GoT ending?

I think this is more closer to Xena and those other 90's fantasy/action shows than GOT. But it's much better than those shows were.

the next worse fantasy show ever? well, it's hard to beat got