Summary
This past season was the first season that Thanasis ever got real minutes, and he actually showed some things. He plays hard, defends well, and finishes decently at the rim. However, that's about all he has going for him. He doesn't have any sort of outside shooting ability, and he doesn't make plays for others. He's doesn't have the handle to make plays off the dribble, so he's not going to initiate any offense.

Thansis is also not as big as Giannis, so he can't quite provide rim protection. If he could, he could play more at center which could potentially make him more playable on offense. Thanasis can provide some minutes on nights during the regular season when you're short-handed, but I wouldn't want him to be anything more than the 11th or 12th man.
 
Cap Considerations
Antetokounmpo will be a restricted free agent with a $2.1 million cap hold and Qualifying Offer, and the Bucks will have his Early Bird rights. If the Bucks don't think Thanasis is worth retaining for $2.1 million or more, they may not even tender him the QO, which would make him an unrestricted free agent. If the Bucks re-sign Antetokounmpo using the Early-Bird Exception, they could offer him a starting salary of up to 105% of the average salary this past season (roughly $10 million), which should be more than enough.

Other teams will have multiple ways to Thanasis as even teams without cap space could possibly use either of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE to sign him to an offer sheet or outright as an unrestricted free agent. He also could likely be signed for the minimum..