We know for definite that the game will feature General Aviation (GA) as the starting springboard of the career mode, from which you can expand into a full fledged commercial airport.
My question is, can we survive off GA alone, or will we have to be forced to develop into a larger airport in the future?
Yes, it is possible to survive on GA alone. If you go extreme mode, you will be forced to start with GA only (if you don’t take huge loans) and then work your way up. However, to make this possible, GA parking and landing fees are up-scaled which might seem unrealistic, but otherwise it would be more or less impossible to make money out of them.
Then why would you still want GA flights when you can survive on only commercial and the only thing they do is clutter the runway and not make any money? I would drop the asap then.
You could do that: start with GA until you go commercial then ditch GA. Or give them their own runway
But what would be the point if the don’t earn money? Real airports must be making money out of it, right? Otherwise an airports like Schiphol, with limited flights and nearly full, would ditch them instantly.
You are not forced to accept GA flights. You can build Schiphol from the start if you are in sandbox or easy mode. But some players would like to see their airport transition from a small airfield to an international airport. This is actually quite challenging and you might misunderstood me as you do earn money in GA but commercial is obviously more profitable .
Disclaimer: If you have a super computer 
Just 93 official gates and about 100+ stands without gate.
Should be doable…
Hmm, I might even recommend a quantum computer for that one, I heard they’re easily available.
Well,I just might do something like that, next decade or so 
But shouldn’t it be the point that you have to start small. And earn money to expand. Now you have to start medium to earn money and expand. That’s not really a challenge. Earning money so you can afford your facilities to transport passengers. That would be nice.
Wait…what?
He just said you can start small with only GA, then work your way up. That’s for the people that want a challenge.
Or you go for the easy mode and build medium stands immediately.
Your choice 
But then you’re avoiding building the medium stands. You don’t need to earn money to build it.
I think we are talking about other things here.
You aren’t avoiding.
You start out with small stands for GA. That gives you money, which you save until you have enough to buy a medium stand.
then a terminal
then some fuel services
then baggage handling
That’s what I like. But the question is. Is that possible ?
yes…
Start with the Extreme option and that is basically what you will have to do.
Start with the easy option and you can get going with some medium stands, jump starting your airport
Some people are so slow lol
I just assume i didn’t explain it correctly. what’s clear to me might not be clear to someone else
That’s not really nice to say.
I ment it more as researching the passenger side before being able to go there.