ICOs will never end because most of them accept the option to pay with cryptocurrencies like Bitcoin, and is almost impossible to stop people from transferring bitcoin to any investment they want. But of course the ICO's will lose strength because countries are prohibiting their citizens to invest in ICO, or at least deeming they illegal, so they could not count on the legal system if things goes wrong. Of course the legit projects always will find a way to rise their funds and thrive no matter what.