What would it be like now? I imagine it'd probably be something like the following:
Odds are high that Chris would be in some of the really mediocre C string porn (at best) and he'd end up getting addicted to drugs and pimped out to various people because they'd tell him that this is "where the real money is at". Chris being Chris, he'd probably get into drugs by someone giving him something at a party- most likely a hot girl or someone that he really wants to like him.
But odds are that he wouldn't get into porn or even into real prostitution, as he would be too cautious and too picky. Chris isn't the brightest guy out there, but odds are that he wouldn't get into any of that willingly. He'd have to be forced into it, essentially, and I don't see anyone going out of their way to do that.
I see him dressing in some of Barb's clothing and putting on a wig to escape detection. He'd be fine until he heard Snyder and then Chris would do something that would completely give himself away, such as knocking over a display or otherwise acting extremely conspicuous. Or he'd go up to the register and pay with his or his mother's debit/credit card as opposed to cash.
Artist's depiction:
If it actually happened? Either Chris would have had to have cleaned himself up or Megan would have had to have received some brain trauma.
Assuming that it's the latter, odds are that Megan would just settle into a life of mediocrity at best. She'd probably have her hands full with the stress of cleaning the hovel and caring for Barb. After all, even though Chris expects to be the stay at home dad, Megan would be expected to do most of the "woman's work". I can see her constantly at odds with Barb, as Megan would probably be sneaking out a bag full of garbage for every one that Barb brought in. Plus Megan would likely resent her since it's unlikely Barb would allow Chris to move out with Megan unless there was a great argument.
Eventually Megan would find that she's really only alive when she drinks and takes a prozac or something to relax. Eventually she'd OD and Chris would find her stiffening body in the bathtub and have to call the police while Barb tries to keep the children from walking in and finding their rapidly cooling mother. There would be a funeral where Chris would shove the kids onto someone else. Odds are high that he'd allow Megan's family to take the kids "for a few weeks while you heal", which would turn into them eventually filing for custody since Chris's house isn't fit for a dog. Megan's brother or another family member would possibly drive to Chris's house and beat his ass, but that'd be a bonus.