If it makes anyone feel better I spoke with Miss Cleo last night. She told me Indigo retained the banks as negotiating leverage with United because talks were stalling.
In all seriousness, though, secrecy is absolute paramount with Franke. The leaked report to NYT (retaining specific banks, dollar valuation) was on purpose. I'm guessing he did that to begin messaging investors that there will be an IPO. It's possible he is still in talks with another carrier but who knows.