I don't think she's right about the calculation.
But just in practical terms, if you live in a Democrat state, you may still have a chance of electing a Republican by popular vote, but you will never do so by a vote of the state legislature.
Not unless returning election of senators to state legislators made state legislatures and state elections function in a radically different way.
And if you live in a Republican state, the Senators the state legislature sends to Washington would tend to be part of the club, people who've paid their dues to the party machine, not those who would shake things up.
Look at States that traditionally vote for Repub candidates versus the Senators that represent them. You have that extremely backwards.
Democrat States elect Democrat Senators. Republican States ALSO elect Democrat Senators (All politics are local and all of that urban center stuff).
Bingo. States like Massachusetts, Illinois, New York, et al, would never have the most remote shot of electing a Republican again if it were up to the legislature. Look at Hawaii, there are ZERO Republicans in their State Senate and very few State House members. That state won’t ever elect a Republican.
You absolutely nailed, too, that GOP states would send types like Flake, Murkowski and McCain to the Senate. You couldn’t even get a Conservative out of Texas or Florida. The creepy Crist, who switched to the Democrats when the Republicans refused to nominate him for Senator - he’d have been elected by the legislature to the Senate and still voting virtually the same way — far left — as he now does as a useless freshman House member.