Lukaku-Firminho were brought up as hypothetical points on a scale that goes from less technical to most technical. less compatible to more compatible. We probably agree that players have different degrees of technical talent with their first touch so it shouldn't be too far to believe that players will also have different degrees of compatibility for a style of football completely dependent on their touch. Controlling the ball in stride is hard, having them make inch perfect passes with their first touch is difficult, doing it under pressure in a match is talent.
This is before factoring mentals like how quick thinking the player is, some lack proactivity and can only control the ball before finding a pass or they make a mess of it. To sum up my take, no, I definitely don't think these players will all make it for a range of compatibility issues ranging from gash technical ability to low mental aptitude. They might be better footballers for their next team because of training this way everyday but they still won't be good enough to do it in a red shirt.
This one isn't directed to you. For sensitives who get triggered by opinion predictions, calm those tits, yes I'm also perfectly aware I might turn out to be wrong in the end and they all become blazing success stories but I'm not betting on it. Expecting ETH to justify every player he inherits is setting the bar too high. Personally think only a few will make it when it's all said and done.