In instances like this, producers do tend to use the performer playing the role at the time of the recording rather than the role's now-gone creator. It's understandable that they don't want to pay two salaries, but it can be damaging to the final result.
The most egregious instance of this is recording the '93 "She Loves Me" revival and not bringing back original leading lady Judy Kuhn (who had moved on to the L.A. "Sunset Boulevard) to make the recording. It might have been worth the money to do so, as Kuhn's vocals were such a strong element of that production and without them, the CD is far less noteworthy.
