Other rides close earlier too -- check your timeguide on the day you arrive -- all of the headliners remain open until at least 9...
As to EMH -- when they have evening EMH, the headliners will start "stacking" their times after 8pm -- that is, you will see a ridiculous time posted like "60 Minutes" for Test Track's single rider line, etc and they will even "hold" you outside the line to make it look like they are waiting to allow you in because there are so many people in line...once they let you in, you'll find that the lines are significantly shorter than that -- sometimes almost non-existant. They do that on purpose to reduce riders later in the evening. They particularly seem to do it on EMH nights to get the day guests out earlier, to prevent that "lets just ride it" thing...
Note to keep in mind not related to Epcot -- Magic Kingdom ALWAYS stacks their ride times on special event nights (i.e. MNSSHP and MVMCP) after 6:00 -- so you will find that 60 minutes Space Mountain time on those nights at 6:00 is really only 5-10 minutes