If Stelios and family sell all shareholding to one party Easyjet would be in a takeover situation. Th enew owner of the shares would have to make a bid for all shares.
Interesting scenario.
Based on last published accounts 4 shareholders control over 50% of the shares.
Easygroup holdings 26.07
Polys Haji-Ioannou 11.11
Prudential 6.24
Standard Life 7.36
(Standard Life have acquired up to another 1% since then)
Even if he didn't sell then all it would need is one Institution to stop supporting management for a substantial Board change to occur.