It depends on how the gamblers fully familiarize themselves with these new trends, gamblers love to play in a traditional setting online and offline, if this metaverse gambling is easy to understand, no complications and gamblers can easily relate or familiarize and profitable, they will easily get into it, we'll see next year if this metaverse gaming will take off and become a serious threat.
Let's take Axie Infinity as an example. Many people, even not crypto-oriented or familiar with anything about crypto try to enter game and forced themselves to learn because of the play-to-earn- feature.
The same will goes on Metaverse-based games that involve gambling features. Even a gambler is not familiar or having difficulty understanding the stuff about metaverse or NFTs, as long as they see more opportunities to earn here while doing gambling, they will do anything to learn it.
And no. It won't be a threat in the future for usual gambling because features are different.
I'd reckon it wouldn't really be difficult, it's only changing a platform plus adding in features that make it seem like it's a whole new 3d world specifically made for gambling purposes. It, at it's core, is still a game. Gamblers in the general sense play gambling as "games", so I hardly think it would be that hard. IF the complications involved let's say, country-wide restrictions, hardware specifications, and many more requirements that would make it a pain in the ass to play, then maybe, but if it was the usual games? I hardly doubt it would be difficult.