That's why I think her destroying King's Landing was idiotic. She turned any possible ally (except Grey Worm) against her before she even took the crown. They told her there was a new prince of Dorne who supported her, the Iron Islands were with her, the Vale. The North wasn't really fucking with her, but Jon was loyal. Tyrion can no longer support her. Neither can Davos or anyone really. So unless she plans to be with Drogon 24/7, she can expect to be killed. She can never rule legitimately.