Yeah I completely agree. I hope we see some really cool changes (that last, I don't want them conveniently undone by season's end

).
One of my slight gripes has been that I've been excited for Caitlin to become Killer Frost since the show started and then they just had that role be taken by her Earth-2 counterpart, so it'd be pretty cool (pun intended

) if the Earth-1 Caitlin is now a villain (which I've been wondering about since they've made a point of having Zoom tell her that she has darkness and the capacity to be like Killer Frost in her, I wonder if that was foreshadowing).
Nora being alive in general is exciting too because it gives us a heap of possible new character dynamics (since we've only known her in flashbacks so far so having her around in the present-day is bound to be interesting).
I wonder if the butterfly effect of this change ends up with the Earth-1 Harrison Wells still being alive? Since Earth-2 Harry returned to his Earth in the finale, it would be a way to keep Tom Cavanagh around.