Audio interface built into midi keyboard connection - is that such a big deal, really.
The flexibility of updating audio interface to higher quality and not switch keyboards seems better to me.
And if wanting better weighted keys, more faders, knobs and pads available you can switch to another midi keyboard without changing soundcard of your choice. And you can select any class compliant keyboard - meaning you don't need vendor to supply specific drivers.
If there were a high demand for this kind of integration there would be these alternatives still. I think most people prefer flexibility.
You can see what this approach with integrated audio and midi did to you - it locks you in and you have to worry about these things. I recently ditched an old M-Audio Evolution UC33 controller - since the latest midi drivers from M-Audio did not work so well with all hosts anyway - they loose contact after a while. I go class compliant stuff all the way now.
Don't worry - there are plenty options - but more flexible ones.