Lightning does not require SegWit, and SegWit already is a compromise on block size by increasing it to 4MB.
Couple of comments.
SegWit does not change the actual block size. It stays at 1 MB. That is why SegWit is a soft fork. Nodes running older versions will still accept it.
SegWit moves some data out of the block so that more transactions can fit into a 1 MB block.
The various versions of Lightning need SegWit to fix transaction malleability. It will be very difficult to introduce a version of Lightning if this is not fixed.