Nintendo are keeping them to a minimal with the DS, which I don't think will ever change for Nintendo and their handheld devices. Though for regular home consoles, there wont be any change in the disc formats, except that Microsoft and Nintendo might adopt Blu-ray in he future because games are getting bigger and to re-enter the cartridge era would be expensive for both the consumer and publisher when there could be cartridges of 15-30GB instead of 256-518 megabits (32-64MB) to the largest that the Nintendo 64 had on offer. Games for the cartridge based consoles proved expensive when there was the cheaper alternative of CD's (now DVD and Blu-ray), which I would stay with the disc format for all the things that wasn't available for cartridges.
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