Nothing will be "locked in". It will always be temporary.
Yes, of course. The LT funds have average maturities of 10 years or more. Average "duration" on one fund, for example is 13.4 years, and "average effective maturity" is 23.7 years. (BTW, I don't understand the difference between those two things. But I understand the overall picture which is that the fund is invested in longer maturing bonds),
So, yeah, it's "temporary" but we are looking for some stability over maybe 30 years, after which the temporal nature of my existence will render all of this moot.