Is there anyone on MN who doesn’t think this is all going to end in tears, and end sooner rather than later?
Me actually 
Personally I think they've both underestimated their "cachet" and their ability to cash in over the long term but that said I think they are now both "in it to win it".
Much like some other high profile couples who weathered "storms" because they knew their "brand" was stronger together than apart.
I think that's true here and also has the added dimension of who now can they turn to apart from each other? They've burned a hell of a lot of bridges across both families and friends (allegedly) and as much as the door has been left open for H, I can't see him living back in the U.K. away from his child until A and any future siblings are adults.
I'm not suggesting it's all going to be rosey - but H made his choice (allegedly despite close friends/family/advisors etc urging caution) and I don't see him returning tail between his legs admitting he fucked up.
Equally M made her choice in literally "hitching" her star to H's - being an Ex wife of a royal isn't in her game plan I suspect and without trying to be rude, as beautiful as she is, in 5/10 years time she's not trophy wife material especially with the baggage of having a royal connection and all that entails (especially wrt to her children).
So yes, I think they'll stick together, milk what they can financially and slowly see their stars start to fade as the next generation of genuine Royals (W&C's children) come into adulthood - whom people worldwide will be far more interested in than a now very middle aged couple on the US speaking circuit rolling out the same speeches that reflect a very rarefied and realistically underwhelming set of life experiences and "achievements".