What if Adam stayed on spn?

I always thought how much spn or actor references could've changed if Adam ended up staying on the series as a regular otherwise a reoccurring guest star. For instance, J2 would've been J3 instead. For me i think tht his relationship with dean might have changed. Imagine if the two teamed up against Sam and played jokes on him, teased him etc. Or hw Adam would interact with other characters such as Kevin, Andy, Crowley, Jo, Jack, Garth and so on. Imo, I feel like Kevin shouldve met Adam since they have many things in common like being forced into hunting, not knowing their father much, having only their mom, so on so forth. Adam definitely had a lot of potential! But thts js me, what's your guys' opinions?