Well, I'm still in shock from the fact that you're not continuing further, though I think it's a wise decision. Too far out and it becomes more fiction than AH.
I do wonder how the Geman Confederation develops without Prussia and Austria, paricularly what happens to the Rhineland.
The epic battles between the Empire of Mexico and the USA look like they will be very interesting, though I'd like to know more about how the former manages to be so stable. Then again, I suppose the later is more stable as well, since we've likely prevented the Civil War. That being said, it seems like slaver will hold on longer.
I'm still curious if reactionary Britain might mange to push Canada into revolting. Certainly the circumstances for the Durham Report have been altered, as have those for the 1837-8 Rebellions. Maybe they're put down and thought of as precursors of the Revolutions of 1840.
Also, what happens with the First Opium War in China? We seemed to have missed that side of the planet.
All in all, a very good TL.