It's quite possible that the likes of Mourinho and Guardiola could go into international management, but only when they've finished with, or fancy a break from club management. I think we can all agree that Martinez, whatever we think of his abilities, or lack of them, genuinely loves football, as do most managers at any level - hence their need to stay in the game. For someone like Mourinho, the Portugal job would be like semi-retirement.
International management is a part-time job with a couple of games against often inadequate opposition and then nothing for weeks, even months, whereas with a club side it's a game every week and training every day. A number of international managers have said how much they miss this activity and I suspect that Roberto does too - Koeman might be an exception to this, having lots more time to get his golf handicap down.
Our Belgian correspondent,
@Armel , has informed us that Roberto has taken on extra responsibilities as technical director, and he does a lot of PR work for them, something he is actually very good at. As well as PR, his other great gift has always been looking after Roberto Martinez and If the right offer came in I'm sure he'd jump at the chance to return to club management, especially if he detects a potential downturn in Belgium's fortunes - a lot could depend on whether they get another easy qualifying group for the European Championship.