Not really, not when the carbon-only team can throw things back over the wall to the legacy experts who promised proper interop. And that the new devs aren't even tempted to solve it on their own, which would inevitably happen if instead of carbon they'd try to achieve the same by sticking to some modern subset of c++. With carbon, the new generation who don't know better don't have to be painstakingly supervised to not use any bad subsets of those "~4 languages". Saving the man-hours that would otherwise be spent on arguing about the exact composition of that subset would likely be enough to make the switch worthwhile (yeah, I might be projecting, I'd get nothing done at all)