This won't be happening. Countries can take regulations, but this will never help them regulate the ICO structure barely. This will only a fear factor for ICO conducters that's all.
They can create companies in Singapour, Cayman Islands etc. They keep it anyway.
You are right, they can control some organization but not all since that regulation is only applicable to some countries, but since majority of ico are born here the bitcointalk can regulate it and to some extend weed out scam ico's
End of ICO isnt really an appropriate word to be used.It maybe regulated but not all countries do really have the same decision regarding on this field on which its really still possible to join or invest on ICO. They might do such act but it cant really stop completely. Scam Ico's cant really be avoided and this is really a responsibility for a certain investor to look at and to be awared of.