"The higher you go the bigger the coaster."
Not to disagree, but I think this is likely to change somewhat in the future. Take a look at Magnum's lift versus Millenium Force's lift, and the angle of ascent. Perhaps by the time we reach the 450-500 foot height, there will have been some sort of 90 degree lift -- like an elevator straight out of the station. Of course you'll still need the run out room, and I think it isn't height that is likely to stop coasters, but speed. The faster you go, the more space you need, but there will be a point where the friction means we can't go faster. If you can reach 150mph (or whatever speed) from 450 feet, and 500 feet is only 152mph, is it really worth it?
It will be interesting -- and thrilling! -- to see what new coasters are developed as we reach limits with the designs we know and love!
-------------
PO!NT OF VIEW - A Different Look at Roller Coasters
http://www.crosswinds.net/~justmayntz/thrills/ Make your VOTE COUNT! Take the CP Coaster POLL!