The default crisis that has struck IL&FS (largest Indian shadow banks), flagbearer of the public-private partnership (PPP) programme, may be the last straw for this once-promising avenue of infrastructureNSE -3.24 % development, experts and executives said, adding that the government will have to take over that role once more. The private sector’s enthusiasm for investment in infrastructure has in any case been waning for some time now, they said.