Every company that doesn’t adapt starts to die. It’s pretty much a law of the economy. TIAA had the advantage of being the biggest fish in the walled-pond of the not-for-profit market for many years, so it got fat because it didn’t need to adapt.
TIAA lost its not-for-profit status back in 1997 and has been trying to catch-up ever since. TIAA also has most of its profits locked in illiquid annuities (TIAA Traditional) which means without a catastrophe, the company will die very slowly.
Imagine TIAA sells BlackBerry phones (annuities) with 30-50 year contracts that people cannot get out of. Even though BlackBerry phones aren’t popular anymore, TIAA is still going to profit for a while because the money is guaranteed to keep coming in. But no matter how many rap songs TIAA funds, the market has already moved on from BlackBerrys.
It’s probable that the rest of the industry knew this and therefore it was difficult to find a CEO after Ferguson with enough experience to fix it. Instead it was simpler to get an inexperienced person with lots to prove.