would players be interested in another 2 or 3 or more expansion packs in the future?
If they expand the gameplay as much as DA, absolutely

.
Eh, as far as I'm concerned, you could take it a step further (or in this case less) than expansion packs, and offer mini-expansions or micropayments. For example, I'd be willing to dish out 5 bucks for more ship jewlry, or for a decent starbase manager, or for a new race or campaign, or for hot-seat ability.
As long as they don't go crazy with the idea, I might be open to it. One thing I don't want is to have to buy hundreds of things to get the game to where I like it. Quite frankly, though, I'm one of those people who really doesn't want one or two things - I want to get everything I can. Quite often, when things are split into lots of pieces, it gets very expensive to buy everything. I guess I'm opposed to such a system.
And I definitely do
not want to have any "subscription" items where you have to keep paying for it to use it. I've played a MMORPG called "Silkroad" where you have to keep re-buying a very useful "pet" every month to keep using it. It's pretty annoying and a drain on the wallet. Eventually I just stopped paying to renew the pet - it wasn't worth the hassle and eternal money drain.
As far as good vs evil, I think it should generally go like this:
Good:
+Greater long term benefits
+Large benefit on the civilization as a whole
-Lesser short term benefits, maybe even short term drawbacks
-Lesser benefit on individual planets or ships
Evil:
+Greater short term benefits
+Greater benefits on individual planets or ships
-Lesser long term benefits, maybe even long term drawbacks
-Lesser benefits on the civilization as a whole
Neutral would, of course, be somewhere in the middle of all of the positives and negatives.
. . . and that's generally how good vs evil works, even in real life - evil things may produce short term benefits that usually affect the individual, but always hurt society (and even the individual) in the long run, especially if repeated.
For example, stealing stuff from a store may produce short term benefits for a single person, but take into account that a lot of people are stealing and that it is often repeated: It eats into the costs of running the business, inflates prices for honest consumers, and ultimately hurts society as a whole.
Obviously "good" wouldn't be good if there weren't any benefits. There are both benefits to society and to the individual. In my stealing example: If stealing is lessened, it will mean lower prices and produce long term financial benefits for both the business and consumer. Also, there's a clear but often overlooked benefit to the individual: There's no risk in getting "caught" if you never did anything wrong in the first place. People who are good are very unlikely to have the law breathing down their backs. Sound pretty trivial to me, but I'm surprised how many people forget that.
Anyways, yes, I'd be very interested in future expansions

. So far, it's been a great game and I definitely look forward to future developments.