Well based on my friends and family, who arent that big on the X-Men films (I think they feel they have to like them because of me >
) Most of them were like
"I wish there was more of the bit with Storm and Magneto. And what happens in the future!".
Then because there was such a huge cheer for Cyclops and Jean's return at the end clearly showed me at least that even though Cyc has been minimal in these films, people were happy for Marsden's return, and to me that means they would welcome another OT film or their involvement at least.
I think because people expected Fass, McAvoy and Laurence they didn't really have the investment in them that they had for when the future was actually changed. Regardless of who you think is a better Xavier or Magneto, it was McKellan and Stewart that started it and so people naturally want to see what happens to the "original" characters that have returned after such a long time.
FOX would be kinda crazy to me to not capitalize on the fact the crowd still like the OC. People even liked the fact Halle seemed more fierce in this and cut her some slack! People cut HALLE slack! if that doesn't tell you that they want more of the OT I don't know what does hahaha