It's obvious Miz is Riley's life preserver. Let's face it, there were three options for Riley and WWE following his run on NXT: 2. 1. Get released outright. 2. Be a directionless undercarder out there on his own continually punished for a good while for his screw-ups, which would have been disastrous. Or 3. Try to limit the damage, don't let him wrestle on TV for a couple of months (barring that one street clothes squash encounter with Bryan) so as to save himself the possibility of embarrassing/hurting someone or himself since it seems like he suffered from nervousness in the bigger situations on NXT and Raw's a lot bigger than NXT, punish him a bit by having Daniel Bryan take him to school and be perceived to be Miz's lackey, and go from there.
Riley got by far the best of the three options. And now he can thank WWE for going with Route #3 because rather than even considering releasing him following the DUI incident (let's not forget the context--he was already on a kind of "probation" of sorts following his little series of mistakes), he's as safe as he could be.
As for the questions about him having to be Miz's bitch for the rest of his career, let's not get carried away with ourselves. If Riley can get on a positive roll and further find his own niche, I'd say his current role's expiration date is at worst around 14 months away. And honestly, if I'm Riley, I'm okay with that. He may be in a doghouse not unlike Miz, told "one more fuck-up and you're gone, we've just about had it" (with Miz it was just overall performance, not the string of incidents), but logically the higher Miz goes, the higher Riley goes. Triple H being at the top of Raw for literally half a decade ensured that if WWE didn't screw it up, either Randy Orton or Batista would become huge through an inevitable feud with their former master. They messed up with Orton but got it right with Batista and consequently he became the #2 star of the company for the next half decade. We were talking about how Luke Gallows could've become potentially big so long as WWE kept CM Punk and the SES at the forefront. Well, instead they made Punk increasingly less relevant and then shot a cruise missile into the whole scenario by having Big Show become a one-man wrecking crew for the entire faction, fundamentally belittling both Punk and the SES to the point where it became almost a punchline. When that happened, the dreams of Gallows were flushed, and now he's unemployed.
If Miz becomes an entrenched main event talent over the next 14 months, and Riley's still with him, I think you could be looking at Riley vs. Miz in a marquee match-up at Wrestlemania XXVIII. That's quite an upgrade over where he is today, don't you think? He just needs to get his house in order, and we have to be patient, just for once.