Indycar will not get any bigger if they just ADD your favorite circuits to the future schedule. Neither aerokits or more faster cars (Remember that Dario and Tony ASKED for a little bit slower car because of Dan's death)
The real ideas to fix the series are:
1) ESPN for all races with NO conflict with Nascar
2) Get a new titlle sponsor with lots of extra money (and 'know how') to invest and promote the series. (like RedBull, CocaCola, HotWheels)