Going back to OP, my answer would be as a content FSX user with a world of OrbX add-ons (all of them in fact) if Orlando Cityscape is anything to go by I wish OrbX WOULD abandon FSX. All their other products give me huge grins in my sweet setup and almost limitless opportunities to fly where I want. Orlando makes me depressed and probably determined to quit my OrbX completionist obsession while I'm ahead. 

The scenery is grossly under optimized for actual flying. Ignoring the ludicrous load times when loading the sim, flying INTO the region in FSX is impossible. By that I mean the scenery loads so slow in the background that it's only half finished on rollout! I was flying in from KMBS, a GOOD add-on in the PMDG 747-400 and experienced a problem I never have before with FSX and OrbX. Scenery slowly disentegraing outside the aircraft into a green blob on the ground with skeletal airports. External views wreck the flights because once the shock of seeing how bad the area looks with NO scenery loaded wears off and you get back in the plane all your panels are gone and replaced with blurs too. Whereas this minor issue is fairly common with FSX but only lasts a couple seconds at most with any other scenery, with Orlando that's it, flight over. Unbelievably bad. Anyway, point made. Maybe the scenery is OK for vfr IF you start and finish in the same area. I love to travel though making this area a no fly zone. 

Oh BTW please please let's not have any "my sim is better than your sim" comments here. I'm AGREEING that my sim just can't cope with this monstrous scenery so can we limit the discussion to OrbX development strategy as whether they are abandoning FSX? I could make the case that Orlando is deliberately bad to persuade FSX users to just give up rather than complain they will get no more scenery! 

I think it's difficult to get the level of detail right and still get performance with terrain. If we had a 50Gb point-cloud of a dustbin then look close enough it's obviously not real. FSX detail was just touching the steep part of an exponential curve. Increasing detail even slightly is exponential, a careful balance is required across different regions since density moves us up the curve a little but increases load a lot. FSX was a little early with the performance requirements of the scenery back then and now it's the turn of P3D. Maybe we shall see these size sceneries consumed with reasonable performance like older scenery, all in good time.

Russell, I suppose it depends on the customer base.  How many FSX-FXS Steam owners have switched over to P3D?  Companies cater to the customer base.  Or is Orbx hoping to force their customers to move over to P3Dv4 if they want to continue collecting Orbx sceneries?  I had all three, FSX, P3Dv3 and P3Dv4.  I gave my FSX Gold Edition to a young man in town who is saving his money to take flying lessons.  I remained with P3Dv3 simply because I wanted to keep all the aircraft I had collected.  Then this thread morphed into a P3D performance thread.  I did a performance comparison test between V3 and V4 and decided the performance improvement in V4 was enough to make it my primary sim while retaining V3 for older aircraft.

As an old sports car enthusiast I cringe when I see Jaguar and Porsche SUVs.  But they are going with what the customers want.  That's what it appears Orbx is doing.  Moving up with the new simulators.  It would be a shame if they abandoned their old customers who still prefer FSX and P3Dv3 but if that's what they are going to do then either be satisfied with what Orbx scenery you already have or move up.

I gotta say Sun Valley is an outstanding piece of work.  I'm somewhat familiar with the area.  I've never flown into it but I have driven by it a number of times.  I do wish a version of it was compatible with FSX and V3.

Noel