I preferred the assassin meta, I liked the plays, mechanics, pressure and strategy of that meta far more than the current 'meta' cycle that we're going through now.
Riot can simply revert assassin nerfs, item nerfs (lich bane) or game changes (vision changes, exhaust and heal buffs, mercurial scimitar MS buff) or buff assassin numbers again.
Ziggs got some quality of life changes, Syndra and Orianna are also popular and they're hell for assassins to fight. Dorans shield use to be able to prolong an assassin in lane so they couldn't be bullied by Ziggs/Syndra/Orianna easily low level but Dorans shield is a lot less effective at that. The meta is mostly focused around wave clearing and rotations with team fights than vision control (the way it was in S3) with assassin picks. Assassins are more risk than reward in general and there's a few ways to fix that.