The 62-year-old looks poised to take the reins at Old Trafford after the departure of David Moyes in April, but first has to guide Holland through the World Cup in Brazil this summer, as they take on Spain, Chile and Australia in Group B.
Throughout qualifying, van Gaal utilised a 4-3-3 system where Nigel de Jong and Kevin Strootman would protect the back four with Wesley Sneijder playing further forward, supporting the front three of Arjen Robben, Robin van Persie and Jeremain Lens.
Yet Roma midfielder Strootman is out of the tournament through injury, and van Gaal is now reconsidering his tactical options – a risk given how close we are to the start of the World Cup.
The proposed switch is now from the 4-3-3 to a 5-3-2/3-4-1-2 system is one that has been made popular after the success of it from Ronald Koeman and Feyenoord this season, and if it proves to be successful in Brazil, could van Gaal use it at United?
The system needs a sturdy yet mobile back three, marauding wing backs and a technically gifted No. 10 to work. Starting with the defence, United have let Nemanja Vidic and Rio Ferdinand leave the club on free transfers, and whilst Phil Jones and Christ Smalling have shown flashes of promise this season, it's an area van Gaal would have to strengthen and add to if he is to go with a back three – particularly as Jonny Evans is the only other recognised centre half at the club.
At wing back, United could certainly use potential signing Luke Shaw on the left, taking advantage of his attacking prowess, but the right side is less clear. Rafael has had a stop-start season and his future could lie elsewhere, whilst Antonio Valencia may be better suited to the role having featured at both right back and on the right wing.
In the No. 10 role which Sneijder plays for Holland, United already have the perfect candidate – Juan Mata. The Spaniard has regularly been used out of position in United's 4-4-2 system, but the switch to 5-3-2 with him in behind the strikers would be ideal for the former Chelsea star.
Van Gaal has shown the ability to adapt his tactics throughout his career, from his famous 3-4-3 at Ajax to his more recent 4-3-3. Whatever he decides to go with, United will be far more attack-minded under the Dutchman than they were under Moyes.