tbh, i don't see either of those coming. I'd love to have hamsik, diego or aquilani (not so much for vdv and lampard) but as far as hamsik goes; napoli are clearly building the squad around him and they have a long-term plan for him it seems. plus, they are (financially) seen not in the position anymore that they are bought out half the squad at the end of the season. The management and their coach clearly stated that hamsik was not to go away. Now, we all know what these statements mean (nothing) but i'd say, if hamsik himself does not express his wish to come to us, then we won't see him here (sadly).
As for Lampard; he will stay at chelsea i think. How often has this subject been discussed. He said it a thousand times, that he's happy and bla bla. Ranieri doesn't matter at that part, should he go away from chelsea, then he'll end up in Barca or something, because deco does not play atm.
Vdv; he's good, but will probably end up in spain.
Aquilani; i think he'll stay in roma. Roma to me are very clever as far as their team-building goes. They seem to reinforce their squad very precisely but without spending much, and with choosing the right characters. I don't know how to explain myself but if i see the roma-squad, i can't think of anyone leaving. They have like 11 players who are to roma like del-piero is to juve. I couldn't imagine for example rossi leaving, let alone totti. They all are very attached to roma, and i think aquilani will soon be a included into that group.