Probably a sight less than have gone to the IPL. There is no non-financial reason why players should be penalised for playing in the ICL. It is only the greed of the BCCI, who were whinging on and on about the 2020 world cup because they hadn't played it and so were against it, then found it was popular too late and were desperate to cash in but were beaten to it.

As for these arguments that if it happened in England or Australia it would be fine, thats a very weak argument. Domestic competitions in other countries do not invent and sell off teams to rake in TV rights. Competitions are played with teams who contribute to player development, work on developing cricket in the local area and exist all year round. If the Indian states were playing in the 2020 then fine, but can you imagine English 2020 being played between Manchester Mavericks, Leeds Lions, Birmingham Boshers, London Lettuces, Norwich Knights, Newcastle Not Outers, Bristol Bullseyes and Swansea Streakers? Especially if the players disappear back to a proper side for the rest of the year.