DVD is becoming near-standard on laptops and new PC's. The only problem is that PC's aren't becoming obsolete as fast, so they're not being replaced as often. Look at your local Best Buy and look at the DVD vs. VHS real estate. The format is here to stay, though the adoption rate is going to be a little slower on PC's.
As for Mini-Disc... check your local radio station. Chances are they're using it. It's far from dead, it just isn't the consumer format everyone was betting on.
All that aside, the most complex games aren't on DVD now, so why would RCT need to be?
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Jeff
Webmaster/Admin - CoasterBuzz.com