I don't see how their popularity has suffered too much over the years. Worldwide sales for their albums since Bounce have been rather consistent up until What About Now. There was a drop off there, but I would assert that has more to do with people moving on from the CD format more aggressively since 2013.

Strictly subjective, but my issue with Bon Jovi is 2 fold:

1. Change in lyrical songwriting. Bounce was the post-9/11 album, dark and angry, the antithesis of Crush. Most subsequent albums have followed this darker template, albeit with an ongoing U2 musical background. The deterioration of Jon's voice only exacerbates the issue.

2. Playing to his middle America, aging base. While nothing he's done since These Days has connected with me, I can see how he's tried to stay relevant to his audience similar to his idol Bruce. That means a faux-Country album, duets with Sugarland and Leann Rimes. If rock radio would abandon them, then he would go to another format. The audience would still find him.

I think bringing Richie back might help. I think moving far and fast from John Shanks might help. I think a full album of Jon/Richie/Desmond anthems might help.

Of course, this is Jon Bon Jovi so all of that is highly unlikely.