With the world cup the schedule is hard, we need all players available, everyone will be getting their fair share of game time, both Walker and Cancello ran out of gas last season and the year previous, we got away with it just, Walker is not getting any younger, he needs looking after.I agree that we need to sign a LB but we got until the transfer window closes to do so.
Walker and Cancelo are still two of the best FBs in the league and would probably be starting the first few games regardless of whether a new LB joined.
For me the big issue at FB arises when we need to rest/rotate players. Luckily for us, we probably won’t need to do that until after the transfer window closes and the issue will probably be resolved by then.