I don't think we need to talk too much about Girona, I mean their performance will never be the same again next season. There will be players who come and go, as will coaches, so changes in their strategy and opportunities next season are very possible. Think of Girona as a seasonal team that is only good this one season and returns to their habitat next season, unless they get a big investment from their owner.
I think you're wrong about them. If you've been following Girona you'll notice that these change in performance started since last season, even though they were not nearly as good last season. I'm not saying they'll continue to remain a top 4 team or a team that will fight for the league, but they won't just go back to being a relegation team next season. They have rich owners, even though they can't generate money as the big teams, their investors won't let their investments go to waste.
I believe Girona would strengthen their squad in the next transfer window. They know they areas they're lacking, like the defense for example.
What I'm sure if next season is that Giron would be among the teams in the top 10 and I believe they would even fight to be get a spot in Europe. They have good management and if they make the right decisions, they can have a very good future.