I wouldn't call it a game, but I don't remember it ever being a slideshow, even when it first started 10 years ago.
On that note, Second Life isn't really all that CPU intensive. It only has an 800Mhz CPU and 512MB of RAM requirement and I think that may be pesimistic. I think the only reason it's not running on the Pandora is because no one has put forth the effort to get it working. I guess the screen resolution may be a blocker but otherwise it's all just coding problems, porting it to OpenGLES (or using lunixbochs' glshim effectively): these are the same problems the Pyra will face.
So to answer the question, will it be powerful enough? Yes, absolutely. I fully believe the Pandora is powerful enough and the Pyra will be at least twice as powerful and upwards of 6 times depending on threading.
Whether it will actually happen is another question entirely.