We have a good number of lecturers in addition to tenure-track faculty members (at Princeton CS). They are extremely good and greatly decrease our load, so we haven't faced burnout so far. That said, enrollment was up so sharply this semester that we had to hire lecturers on a month's notice, which is kind of insane. Also, we have a new industrial Master's program which lets us increase our number of TAs.
In spite of having adapted in all these ways and money not being a problem, we know that this won't continue to scale because enrollment growth shows no signs of slowing down. We're not sure what the long-term solution is going to be. Online education is part of it (and we're on Coursera), but so far we're not using it in a way that decreases our teaching staff requirements.
Strange times.