Not sure that something big could happen AFTER this season! This season is way too bad to remember but the future is not bright either.
It's not probable for a team to have a terrible season and win the next one, but not impossible either.
Only in the last 10 years it happened 5 times in the big 5:
Juve were 7th in 2010/11 --- won the scudetto in 2011/12
Chelsea were 10th in 2015/16 --- won the EPL in 2016/17
Leicester were 14th in 2014/15 --- won the EPL in 2015/16
Dortmund were 5th in 2009/10 --- won Bundesliga in 2010/11
Montpellier were 14th in 2010/11 --- won Ligue 1 in 2011/12
There are many other cases when a team finished 3rd or 4th with 15, 20 or 30 points minus behind the league winner, and won the next one.
Though, all these teams except Montpellier made drastic changes in the summer before the winning season. Except Dortmund, they all changed the manager, and all of them made important changes in the squad. Juve added Conte+Pirlo, Vidal, Licht, Vucinic etc; Chelsea added Conte+Kante, David Luiz, Alonso; Dortmund bought Lewandowski, while Leicester added Ranieri+Kante, Fuchs, Huth, Okazaki, Inler.
Basically, a good coach and two important additions in the starting XI might make everything click. But that's more wishful thinking than probability in our case.