The Battle of Bosworth field didn't involved cataclysmic forces such as the Others, Dragons or Krakens.
I don't mean unsatisfying in the sense that the end will be abrupt and current cliffhangers won't be resolved. I mean unsatisfying to many due to what happens to the characters. I don't believe it's a safe bet that Dany will ever take the Iron Throne, much less live. I could say the same about Jon, but it isn't like Jon wants to rule in the first place. He's simply a man of duty, like his father. The difference is people are devoted to Jon for different reasons than Dany. Dany has power because of fear. No one in Westeros is eager to have their keeps melted by dragonfire, conspirators are only pushed to support people like Dany (and Aegon, for that matter) because the current dynasty has pushed them that way. Dany could make concessions towards the North, Iron Islanders, and Dorne for the sake of ruling over whatever is left.... but who even knows what
will be left when it's all said and done?
I guess I don't think it's optimistic to believe that there will be a Seven Kingdoms left to rule over. We have no idea how long this Winter will last, we're not even entirely sure if the Winters are what they are because of what goes on beyond the Wall, or if the Others simply nudge it along.
An ideal ending doesn't involve popular/good guys win, hated/evil guys lose. This story has never operated in this manner. The ending will almost certainly be bittersweet.