I'm 100% sure that he will improve next year. Not sure if he can rival Roglic/Pogacar in the Tour but he will surely be in some kind of GC battle(top 10). But more importantly I think the quality of races will improve with him. If he shows some form, Jumbo can't use the train tactic again because he will be feared in the time trials and with his weak teams Froome yoyoing Vuelta style on MTF will be really fun.
I think people dislike him because in his pump he was so much stronger than everyone else that everything he did seemed boring but in hindisght the guy is really gutsy and always tried to put on a show. From 2013 he was always the guy who initiated things in races(not only in TdF). Just remember AX3 and Ventoux in 2013, that first Dauphine stage in 2014 when he attacked Contador 20 times

), him destroying everyone on his mother on Pierre St. Martin, Bagneres de Luchon and Montpellier in 2016. His only unremarkable performance was in TdF 2017 but it was obvious that he hold something back for the Vuelta. Vuelta in which after Contador who was batshit crazy and attacked on every elevation he was still the most active rider even if he had the yellow jersey for the whole race basically. About 2018 Giro I will not even talk. That Finestre stage is still the most ridiculous thing I've ever seen. His win on Zoncolan was also a nice one even though Yates gifted that win to him,