I do believe that Kane and Bryan need to drop the titles, as it's obvious that they're needed in the main event, which has been a huge problem with the booking of the titles. WWE seemingly can't book a main event storyline without throwing Team Hell No into it. There are always two random spots that need to be filled in main event, but instead of temporarily pushing some other stars to fill those spots, Kane & Bryan always end up having more important things to do than defend the titles.
I do think the next team to win the belts will be the Shield. But it won't solve the problem with the tag division. If/when the Shield gets the belts it will be no different. They need to get the belts away from the main event guys, because they keep running into the same problem of "Who can beat them?". The Shield has been pushed so hard that no team will be able to challenge them unless they pair two other random top guys together. And the cycle will just continue.