With PG13 not a free agent anymore, they need to move on, and find another all-star caliber player, and Markannen is their next target.
A player who's very versatile, can stretch the defense of opposing team because of his ability to shoot threes, and he's a reliable player in offense as well. Now the question is, "Will the Jazz trade him?" After his amazing season with Utah, do we expect that they will trade him, or they would rather build a team around him. Based on what I'm seeing online, some believe he will get traded, but some believe he will not. It's still not clear, but if the Jazz will trade him, the Warriors will be the front runner.
TBH, I'm not hoping that the Warriors will get him, but I will not be surprised either. He's not at the same level as PG13, but he can still do what PG can do as well.
I saw a fake news report today on Facebook that made me laugh. It said that Thanasis Antetokounmpo was requesting a trade away from the Milwaukee Bucks. Maybe cheap humor at his expense, but I genuinely laughed before looking at the source. If Giannis does sign elsewhere though, what happens to Thanasis?
Edit: Buddy Hield to the Warriors to form a new Splash Bros?!?! Amazing pickup.
We know that Thanasis is being trolled multiple times already for multiple reasons. This is just one of them for sure.

Kind of funny, but unrealistic.
Giannis + Thanasis package. That's what Giannis want if he will sign with another team. It's like "I'll play with your team as long as you get my brother as my cheerleader."
As for Buddy Hield, it's Splash Bros 2.0. Just for context, both Steph and Buddy are the top 2 in most number of three-point shots made since 2017. Hield at around ~1900 while Curry at around ~2100. I expect that the Warriors will go back to how we they became popular which is shooting threes.