I still play FH4 daily, mostly Fortune islands whenever I want more challenging championships. Actually, it helped me develop my skills.
I also play Lego whenever I want some fun without pressure or stress.
Hot Wheels in FH5 was a blast for couple of days. But it lacks the long lasting progress of FH4 Legoland where house building has visual manifestation of player advancement.
I would love to get an expansion in FH5 that can be the perfect substitute for both Fortune and Lego so I might stop playing FH4 and focus on FH5 and upcoming FMS8.
Side note: latly I see more and more players in FH4 expansion. Migh be somthing right Developers got then and didn’t in HW.