This reminds me about an episode a few series ago when Hammond sends the team through the gate knowing he was sending them to meet himself back in the 1960's....yep time travel again...
...on their return to their true timeline, ours I believe!, they catch a sun's flare, and travel into the future..when Casandra, the ickle girl Sam adopted..., is old and grey... She says she has been waiting for them... the SGC is all under dust wraps...and deserted...she then helps them back on their way through the gate using an instant dialer hand device, that those forest people use...
I fancy buying the whole series on DVD...and starting again!