I have two clients, both with multiple D7 sites and both are supportive of this migration, but neither is in a rush. A few sites are simple and could go now, but most involve unmigrated contrib. Undoubtedly I will need to do some of these contrib ports and some are big. I guess Media is already at work? Some sites need LDAP. One has drupal commerce, which I kind of doubt I could do, so not sure about that. Any expectations for an e-commerce system on Backdrop? That site doesn't even do money - they use it to process swag orders for company staff (who are spread out over half the country). Even so, they have a lot of products so that one might just stay on D7 a long time. Probably won't actually dive into any of this till after the NY, but looking forward to it. Does Backdrop do any camps outside of BADCamp?
I noticed that Ubercart has recently been ported to backdrop. If it works reasonably well, it would probably handle your e-commerce, especially if you only need a basic set of features. Drupal Commerce is a much more substantial beast. I am running a D7 site now with Ubercart, and take five or so orders per day. It does everything I need at this point...
There's also a basic cart module for Backdrop: https://backdropcms.org/project/basic_cart It's a smaller and lighter-weight solution than Commerce or Ubercart. If you need something more like commerce, I'd encourage you to keep an eye on BackShop, a project Ryan Szrama (one of the creators of both Ubercart & Commerce) has started.