Atm it's around 18% but I would be very pleased and surprised if it goes to even 25-30%. Also i think we shouldn't compare Cricket with other sports leagues as cricket is a private club IMO, be it ICC or IPL and need a ridiculous amount of reforms.
And one major reason is there is no competition for IPL in cricket so hardly any pushback against the system but If by any chance some other cricket league rises up and starts spending a big percentage on players then there might be some pressure on BCCI, also don't forget there is no player's union in India.
One of the reasons why the share of salary in IPL is quite low (18% is still decent, I would say) is because the BCCI uses a large part of that revenue to construct infrastructural facilities, and to fund domestic cricket. India has the largest and most complicated domestic system in the world with a total of 38 first class teams. And there are U-23, U-19 and U-16 competitions for both men and women. In the end, IPL revenues trickles down to these less known plyers and a part of that also ends up with non-playing staff such as groundmen and curators. In a way you are right. If there is no purse limit, then this distribution will cease to exist and a few top players will pocket lion's share of the revenues.
But at the same time, this is what the BCCI is doing at international level. Rather than sharing revenue with the smaller nations, they are now pocketing 38.5% of the funds. Is it that difficult for them to practice what they do at home at international level?