[AdmSmith]

Tha assumption that the speed of gravity is equal to the speed of light is a cardinal assumption. If the experimental data are different and these data are found to be correct then the theory of gravity according to Einstein is finito and must be replaced by something better.

That is what happened with Mendel's theory as well (it has been refined as you mentioned)

Science is always evolving, no Final Theory exists.

[Dimensio]

Your assessment cannot be correct. In many creationist threads, when creationists assert that evolution is only a "theory", I would throw back that gravity is also a "theory". They would 'refute' my by telling me that gravity is establihsed, proven, a Law. Therefore gravity cannot change. It's been proven. Creationists said so.