I've been playing for 23 years and I expect to be playign for the next 25 so in 2028 I still expect to be at it.
As to game systems - GURPS and WoD have remained the least changed from a systmes point of view since their creation - both systems are playable and have their own appeal and so I think they will be the least changed in 25 years.
D&D will still be around but not likely in the d20 format.
The d20 system itself when divorced from D&D has a lot going for it - When designing D&D there were a lot of design decisions made intentionally to appease older players at the expence of creatign the best system they could. You can see the improvements in d20 Modern. Assuming they continue to refine the system I can see it still around in 25 years.
The Hero system has changed considerably since it's initial release - Each change for the better (IMO) and closer to the potential that I think we all saw when we first picked up a copy of Champions way back when. The system has also become more cumbersome with every iteration. The learning curve for play is steep and that's putting it mildly - Computerization will be Hero's best friend - we already see it with character design software - It has he ability to turn one of Hero's biggest flaws into an asset. It's complicated but there's software to make it easy and it ties to this software for combat and so on and so forth. So assuming that pencil and paper gaming trends towards keyboard and monitor gaming or maybe pda to pda gaming, I can easily see Hero around in 25 years. Failing that I think we might find ourselves saying to our children -"When I was a Kid I only had paper and a calculator and it took me 5 hours to build a character - and about 6 monthes for a fight sequence"
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