The BAA Indianapolis website has a snazzy PDF-format color report about the midfield terminal, complete with very detailed diagrams and computer-sim graphics. If the new terminal does get built, it will be beautiful--rolling atrium roof, long bright concourses. Funny, the landside terminal resembles the T5 plans for Heathrow, I can't imagine why that would be.
Most airport gate leases have clauses that allow the airport to demolish gate space and re-lease it if they want to build something new. If US Airways gets recalcitrant, and the new terminal gets put off, Indy can always just demolish D to build something different, and tell US Airways where to stuff their anticompetitive squatting. But US will be bankrupt within 2 years anyway, so Indy may just wait them out.
I wouldn't give up on JetBlue, LV. They were interested in Cleveland but the incompetent Cleveland airport management fumbled them. JetBlue is interested in the Midwest, as evidenced by their advisory future-city list. At ROC, BUF, and SYR, where CO and US also have flights to NY, JetBlue is doing extremely well.