Sure, if you pick the frontiers of science then their will always be a sufficient deficit of evidence.
However, the bounds on Sagittarius A being a black hole are pretty stringent now. But sure, there are respectable scientists who do not believe in black holes (or think we have insufficient evidence).
But your point is moot. Give us more time to increase the sensitivity of our gravitational wave telescopes and we will even measure the quasinormal mode ringing of a black hole. Give you more time, and you still will not show us a god.
That takes care of black holes.,...... what about the rest that I mentioned.....the make up of 95% of the "known" universe......