In fairness though he was a legend at that club, Martinez does not have anything like that to fall back on.
Lets not kid ourselves, Martinez has a job that all but about 10-15 people in football would love to have. That's a large talent pool to choose from, and Everton should be aiming high in the next appointment.
Get him out now, put someone internal in charge like Unsworth or someone til the end of the season and have the new guy in place to be able to speak to Lukaku etc. before they go to the Euros and angle for their move. See if he can persuade them to stay.
I've said this loads of times, all the money is in the Premier League now. If you're not a manager of Barca, Real, Bayern or a top International side, it's more than likely you'll want to be where the money is. Everton need to get on the top manager train quickly before we get left behind.