OP personally I don't think its an issue as long as your DH is happy with it and you are financially okay - that's actually between you and your DH and you are certainly not unreasonable to consider it.
You might want to think of it less as giving up work to be a SAHP to your teenagers, as "giving up work" - i.e 'retiring".
It might be useful for you to think of it in this way in order to make the decision, because really in a handful of years they may be out the house, and your role as a parent may just about be redundant. By which time you have a several year gap on your CV, possibly an age that isn't as employable as someone 10-15 years younger (I don't know how old you are and perhaps you had children young and that is less relevant - and it shouldn't be relevant at all, but it kind of is).
So would you be willing to retire now?
Another point I'd be considering if I were you is will you be LONELY? If the teenagers are increasingly independent and out more and more, it is loneliness that may be an issue for you, and this very much depends on how much company you need.
Lonlieness is cumulative - the first 3 years may be fine and after that you may begin to notice it. And you may hate the job, but you may not realise just how much "company" you get just from being there and you may not realise how much you need that till its gone.
I am a SAHM and I have to work at not being lonely. People who I know who have never been SAHM's assume its "finding things to do" that I have to work at but its not - there's plenty to do, I'm not bored, the school day goes quickly (mine are younger, I'd probably find it harder to fill the day if they were gone altogether or not coming in till 7pm or something). But its the people-company and stimulation of just general conversation or interaction that I have to "find". And I do find it, and its fine, but it means I have to nurture friendships more than before I gave up work, and seek out various opportunities to do things that I may otherwise say "no I can't be bothered to do that" because I feel I ought to get out and do it and see more people, if that makes sense.
Of course it also is relevant how much company you need. My husband would happily be a hermit, he's an introvert, so he would be going "what?" if he could hear me now 