As a former Lehigh Valleyan (the worst 2 years of my life) and a quite frequent ABE
flier (both commercially and at Ace Pilot Training) I'd be shocked if this happened. DL
has done nothing but downgrade/cut ABE
flights over the past couple years. Formerly there were higher frequencies and CR7's, now it's all CR2's and E135's, and a total of 5 flights a day on Delta.
Common sense would state that if DL
was going to upgrade ABE
it would come in the forms of maybe a 4th ATL
frequency, or CR7's. Or ERJ service to Florida destinations to go against Allegiant like they go against FL
in many markets. They've got CR7's, E170's, and CR9's to go before they would worry about mainline. Nobody gets upgraded from a 50 seater to a mainliner.
Now they only way they could ever add SLC
would be via mainline as I think it would be beyond the range of anything else, but I put the chances of that happening somewhere between a snowball's chance in hell, and an A380 running the PHL