The driver for SegWit seems to be purely LN
This is an rbtc talking point-- it has no basis in reality. Segwit is largely orthogonal to lightning, and proposed long after it. The reason people keep claiming it is because segwit is above reproach and lightning is less well understood and easier to FUD.
Hmm, I suspect actually a lot of people think that because on the Segwit FAQ, here:
https://bitcoincore.org/en/2016/01/26/segwit-benefits/ it says:
Who benefits?
...
...
The Lightning Network
...
Sure the lightning network benefits from segwit, but it is not the only reason (if a reason at all) that segwit exists. If you look at the rest of the document, there are a whole lot more benefits than just LN. The rbtc taking point is that segwit is only for lightning, but it most certainly is not.