Re: How many more movies would you like with >Original Cast<?
FOX just needs to release good films that will really attract to the general audience. Critical-acclaimed films with good actors (having a well-known actor is always a plus), great visual effects, great cinematography, great promotion, etc.
I just don't see how releasing spin-off movies would improve the series especially they gross lower than X2 and X3. They can still expand the X-Men movie universe, by releasing a new X-Men movie with the original cast in every 2 to 3 years. Introduce big villains like Apocalypse, Mr. Sinister, include new members to the X-Men team like Psylocke, give the underdeveloped characters more screentime and role like Colossus and Storm.
Anyway, this film series is probably gonna be rebooted in the late 2020s or 2030s, since Hugh/Halle will be in their 60s at that time, so they might as well release as many films with the original cast while still they look good, while most of them are still willing to return and while the general audience aren't tired of seeing more films with them.