Dany could go across the Narrow Sea on Drogon’s back without her Unsullied or advisors (especially Tyrion), but it seems unlikely she would so by choice. She’s spent five seasons building her army, raising her three dragons, and conquering Slaver’s Bay. It seems unlikely that she would just up and leave without at least putting Meereen to rights.
So let’s say Dany either convinces the Dothraki to let her go, escapes, or convinces them to join her (which would be pretty awesome – an army of Dothraki AND Unsullied? S***, that’s what they need up on the Wall). Once in Meereen, she prepares her invasion of Westeros…finally. She has a decision to make: go by land to Pentos and gets ships there from Illyrio, or build or buy ships in Meereen to make her way by sea, past Dorne and Storm’s End to King’s Landing. Because of all the time she’s invested in Meereen (nevermind the backbreaking task of marching an army by land to Pentos) we’ll bank on the “By Sea” option if she does go back to Meereen. We’ll also bank on a stop at Dragonstone on the way to exact some revenge on the Baratheons for murdering her family and to set up a forward base of operations.
The problem with this is that even if everything went perfectly it would take a ton of time. Excluding Season 1, travel on the show is never condensed (unless you’re Littlefinger). So it would be strange for Dany to go from surrounded by Dothraki, maybe about to die, to “Dothraki? No problem!” Then immediately to, “Well let’s solve Meereen. We’ve only been working on that for two seasons, so we should be able to solve it in an episode and move on to King’s Landing, a now-months-long voyage which has been our goal for five seasons but we’ve only taken steps away from geographically.”
Or have we?