I think that the only way a true top striker will come (Not necessarily an established one, but an up and coming player who are on wages that can be substantially increased without hurting the bottom line too much) is if both Matri and Quag are offloaded.
What I think is going to happen is that Destro (no, he will not be the top striker, but the backup to said player) is all but a formality

, and then you will see another player along the lines of a Lewandowski type of talent come on board to be the main striker.
With a 3-5-2 formation, the SS striker position will be well covered with Vucinic and Giovinco. You will then see the other postion covered by Destro (again as the backup), and whichever new forward is brought on board.
That is just my opinion.
In the 4-3-3, the front line will most likely feature a combination of Vucinic/Giovinco/Pepe and said striker.