To be honest, at this point, I'd rather see Ironclad invest effort in getting a new game out rather than keeping Sins going, patches withstanding. Something fresh - even if it is just Sins 2 with a snappier UI, better graphics, and a few new ships - would do more good, in my opinion.
Well, the way I look at it, the following two things are true:
1) Expansions give IC (and their publisher) a good Return On Investment. This gives them a stronger financial foundation to work on a true sequel or other projects.
2) Expansions are learning experiences, and the more learned before working on a sequel, the better it will be.
Now, at some point the balance tips and they really should work on a true sequel. But I think there's room for one more expansion before going there.
I've voiced my concerns about (imo, significant, otherwise I wouldn't have said anything
) issues with the UI/game experience in the past, so I won't retread that ground. But I will say that I wouldn't expect those issues to be addressed in an expansion... so it's not as though I'm happy with the status quo!