Er, I think Parliament can and will decide whether Parliament can have a veto. They're voting on the Lords amendments tomorrow. If the Commons decides that it shouldn't have a veto (i.e. that it rejects the Lords amendment on a "meaningful vote") and the Lords concurs on the revised Bill, then that's Parliamentary sovereignty fulfilled
The "meaningful vote" is meaningless BTW, because HMG is not going to recommend a "bad deal", and no deal would be quickly followed by a motion of no confidence and a GE.