It would be best to do this alongside a VU relaunch with certain gameplay tweaks and rebalances.
Still, why not just give us the off-season? Off-season ONLY Dominion gets ranked, and they can stream the highest level matches in place of LCS broadcasts. Once the SR season starts back up, Dominion season rewards are tallied and ranked goes back on hiatus.
A small season with unique rewards, nothing else to distract players, SR keeps as only a normal queue to practice if that's what you REALLY prefer. The short time in which to earn something unique would attract even more players, and the lack of other distractions only improves that. You first need a bite before you can hook someone.
Still, we really need a VU relaunch, and the forum is flooded with suggestions (some really bad but others very much good like removing score) on what can be done to improve things. We can take a test year if you want, each patch iterating different ideas and finding what works best. We can iron out the ideas and have the game settled to launch in 2016. Just make sure to reform the champion balance team that vanished for no reason. There are important champion tweaks (see all threads about switching stacking champions to time-generated like GP) and balancing (nerf Urgot, and seriously look at buffing the bottom champions). Get a team working on this together with the community. We can make it great.