I'm not against experimenting a bit now while there's a chance, but I pretty much agree with Cy's earlier assessment: while Morgan may be more ready to contribute to a rotation than Brantley now, Morgan's really more of a center than a forward.
Morgan's (rather clearly) superior defense almost all happens in the context of him playing center. He's looked much more out of his element every time I've seen him play the 4 either in the NBA or G League. Likewise his playmaking and general savvy fit best with the (rolling/offensive rebounding) role that the Jazz give to the center position rather than the PF position.
I don't think Morgan's a better shooter. The early season G-League shine on his 3-pointer wore off over the season. This is not to say that Brantley's a great shooter, just that neither of them are likely to provide what we want/need in this regard this year.
I don't think Quin will do it, but I wouldn't mind seeing a whole scrimmage of Brantley and Morgan rotating at the 4 position, just to see what things look like with them. However, I wouldn't expect the experiment to be successful -- it would just be something I'd want to see out of curiosity.