Re: No Aikido dojo - what now?? :(
I do know more than one person that is pretty darn good or that I would consider "shihan" level that have pretty much gotten there with only an aikido background.
I don't think you can draw a correalation necessarily based on previous study in other art verses none.
that said, I don't think it hurts you to have a background, and I do feel that personally that at "some point" you really do need to spend some time grappling or doing judo type MA as I believe it can lead to a faster learning curve martially.
In the situation the OP brings, I think it is better to do something rather than nothing and that an art like judo will serve to develop a good base to build aiki upon.
I agree that eventually it is all aikido if you are doing it with aiki as aikido is simply a structured methodology or pedagogy that encourages the development of aiki if you are training it correctly.