They could play together in a 352, but that will mean Rashford and Martial will inevitably struggle to get enough minutes to continue their development and justify them being here. Our lack of quality wingbacks with solid if not fantastic delivery makes it near improbable we will continue permanently with that formation anyway.
That is the case too in a 442 too. It could be a great remisence to the two-striker era but for our lack of a genuine winger(s) capable of whipping in crosses if not getting chalk on his/their boots - which is a necessity in a two-striker formation.
Our current wide options, Martial, Rashford, Mkhitaryan and Mata are all inclined to come infield meaning it will be a 4222, but we don't have the luxury of rampaging fullbacks to play that formation; and in the case of Rashford and Martial, a 424, a formation that has hardly been tried nor trusted in the Premier League.
All points to Jose's favourite 4231, meaning Zlatan will be giving the luxury if not restricted to the No.10 role behind Lukaku. Although he's got great technique, but there're doubts he has the creative awareness, mobility and vision to permanently and consistently pick out passes from that position.
Zlatan in the No.10/SS role in the De Piero and Baggio mold is probably the way to play him together with Lukaku; and uncomplicated by our lack of a genuine No.10 and the fact it will allow Martial and Rashford to continue their campaign as the battle for a dominant spot on the LW heats up, it looks the best bet.
Martial and Rashford should be encouraged to stay wider and provide crosses too, to compensate for our wide deficiency.