Don't settle. It's not fair on yourself, it's not fair on him and it's not fair on any hypothetical children.
Can entering into a more transactional arrangement for the sake of a family work out? I guess, but be under no illusions that it's the easy way. Think about everything settling will entail.
You'll have your relationship tested by sleeplessness, conflicts over who's pulling how much weight, different parenting styles and negotiating in-laws. That's a grenade for most loving relationships. You won't have that foundation to fall back on.
As the kids get older you'll find yourself more and more lonely. You'll have less romance in your life and less companionship. You'll end up living with someone whose presence you tolerate at best, resent at worst.
The sex will definitely, 100% not get better.
One or both of you will probably meet someone in your 40s who gives you everything your partner doesn't - care, attention for who you are. One or both of you will probably have an affair.
You'll either divorce or somehow survive it and end up as one of those old couples who clearly can't stand each other any more but are too lazy to cut the cord.
Here's the important thing, you won't get to complain about any of the above because you know right now you're settling.
In fact, I'd say that if you were to settle you'd have to commit to a path of radical honesty with each other, and it's fucking hard work. You need to go through all of the potential pitfalls above, and probably a whole lot more, and sort them out in advance. How do you feel about an open relationship, for instance? What happens if you commit to this but one of you catches feelings? And if you're to do this you need to start right now by telling him you're settling, and hope to god he feels the same way.
To settle for someone who thinks you're committing to them because you really love them is disgusting behaviour. Could you tell your partner everything you've told us?
There's no such thing as "the one" and no guarantees of anything if you leave him. So no, you might not get your family. I would encourage you to start believing that even if you don't have children, you can still have a full life and contribute to society.