You're right. I'll give him 4 years. But one of the following will then happen:
OSU gets investigated again for major illegal action and/or recruiting benefits and he is let go.
OR
OSU's major (And mounting) off the field issues catch up to them and he is let go.
OR
Once his top inherited QB Braxton Millers leaves (BG QB, Smith at Utah, Leak/Tebow at Florida), Meyer will somehow have "health issues" which he will start taking off. Once he comes back, but the team continues to struggle (Like Florida), he will then leave, citing the aforementioned "health issues".
So yeah I'll give him 4 years. The only question is will he win a NC before he leaves. I am inclined to say yes due to the special, all time great type of college QB he has inherited, but the Illini have Aaron Bailey and others coming in, the Michigan hype train is back, etc. etc. Plus the B10 as a whole is getting much stronger, and will be stronger than the SEC was when he was at Florida. We'll see. Should be intereresting.