what are typical ranges of sales commission (in a situation with
commission-only compensation) for corporate sales (i.e., requiring
significant effort and time per sale) that create an ongoing revenue
stream (and none or only small upfront revenues) and have high
margins?

My guess is that too get a good answer you will
need to spell out a couple of things better:
1 - Product or service being sold.  I have heard
of 2% and up to 25%.  Depends on what.  People
selling planes or people selling shoes are paid
differently.
2 - A friend of mine and I were discussing this last
week for something he is doing.  The questions become
who pays for what, and who gets paid for what.
If you will earn some kind of residual from that account
forever, then obviously that would be less then if
you get a 'bounty' for getting it open.

Never worked in sales, nor do I expect to in 
this lifetime, but have seen a lot of different plans.
Good luck.

Sales commissions for stockbrokers range from 30%-40%.  This can
create an annuity, as long as the client stays happy and stays put...

Good luck!