Will Sion see competitive play?

There's a strong chance he will. Sion's a dangerous initiator and tank, both of which make him clearly viable in the current meta. He's on par with Malphite and Amumu now.

NB3's been playing him a lot in PBE, he's been saying how Sion is actually going to be in his jungle rotation as one of his picks for mid-high Challenger Solo Q, so he's definitely strong. Competitive and Solo Q are completely different games though; I don't see him being a common pick while Lee Sin/Elise/Kha'Zix/Rengar/J4 exist. Still, the fact that he can lane gank from base is pretty powerful.

4 secs of stun on a tanky aoe champ..... Yeah I can see him being played.

In my views, he won't. A good team deals with him so easily it may as well be a 4v5.

He has strong tanky/ damage attributes, however he has a difficult engage/ staying with champions as well as no dissengage which would make him unappealing in LCS+ play