I'm currently making my way through the original series as this new show airs... I'm taking my time with it. Right now I'm finishing up season 6. There was a moment where Ellie told Pamela Ewing that 25 years down the road instead of Bobby and JR fighting over Ewing Oil it would be Christopher and John Ross doing the same... kind of incredible foreshadowing as that episode aired in 1982!
That wasn't Pam, it was Sue Ellen. It was during the big brouhaha over who would get control of Ewing Oil during the year-long contest (as stipulated by the codicil in Jock's will) between Bobby and J.R.
The contest brought out the worst in Bobby, and Pam saw it for what it was, and was also (with a little help from a scheming Katherine and J.R.), what led to their first divorce.
Sue Ellen, meanwhile, stood right by J.R.'s side during the contest and even helped him. That was why Miss Ellie was giving Sue Ellen the talking to in that episode, and you're right - it's crazy to think that was 30 years ago.
Cynthia Cidre screened the entire original series before conceptualizing the new show, so I'm sure that scene was very powerfully on her mind when she sat down to write the pilot.