Converting Tub to Shower

Hi, Great forum, full of information. My question is regarding the remodel of a bathtub into a shower. The contractor doing the work said that the drain does NOT need to be relocated (as it is in concrete and would require a lot of concrete breaking). He said that as long as the slope is good, it will be fine to use the existing drain even though it won't be in the middle of the shower. Will doing it this way cause any future problems?
Thanks

First, in most jurisdictions, they will require the shower drain to be 2" vs the tub which is 1½".

It is OK for a shower drain to not be in the middle. If it is too close to one side, it can be difficult sloping the tiles to the drain if you are doing a tile job.

IF it is a standard tub, then the drain will not be in a location where it could be used for a shower, so you would have to break up some floor anyway.