Now I know you're probably thinking "why would Frontier JetExpress want to serve DAL when Frontier already serves DFW?" Well, for the same reason Continental Express serves DAL and Continental serves DFW. It gives people who live closer to Love Field a choice.
All Frontier JetExpress would have to do would be run 3-4 roundtrips per day to their hub in Denver. From DEN, Love Field passengers could make connections to other points throughout the west. The limitations of the Wright Amendment would not apply in this case, because the first leg of the trip would be on an aircraft with 56 seats or less, so the passenger wouldn't have to buy 2 separate tickets and claim and recheck their luggage in DEN.
This, I think, is why Continental Express' service out of DAL has been so successful. Lots of folks take Continental Express to either IAH or CLE, then connect to other Continental Express/Continental mainline jets to other destinations all on one ticket and without having to claim and recheck luggage.
Not only is Love Field more convenient for a lot of wealthy people in Highland Park, but getting through security would probably take less time than at DFW. Obviously Frontier JetExpress wouldn't be operating out of the West Concourse which is used by Southwest. They most likely would operate out of the North Concourse, where Delta Connection has a handful of flights to ATL, the East Concourse where Continental Express has 12-15 departures a day to IAH and CLE, or Legend's old terminal that no one is using at the present time. Since there's not much traffic out of North Concourse or East Concourse and none out of Legend's terminal, security lines would not be an issue.
If Continental Express can make DAL-CLE work, then I don't see why Frontier JetExpress couldn't make DAL-DEN work.
Just my 2 cents.