This engine deal is now popping up everywhere. Personally I think its a bit too complex. Honda delivering engines, MacLaren delivering gearboxes and Torro Rosso the chassis and body works. Personally I can't see how MacLaren will contribute to development during the season.
I remember when the organisation where I work decided to buy a new telephone exchange installation, but kept the same data supplier and decided in all wisdom to buy the telephone sets themselves. The data supplier blamed the company who delivered the exchange installation and this company blamed the manufacturer who made the telephone sets. Nothing ever worked and nothing got repaired.
Its is already difficult to develop a car with two parties involved. It will be very complex to develop a car with three parties involved. Especially when they all have different interests........
But perhaps it will work. When Honda brings in a lot of money I think Torro Rosso will give it a try. From Honda point of view it makes sense, because I think this is the best team they will be able to find for their engines as most others teams will be very reluctant to take a change on the same misery MacLaren had for the last years .
Just my best guessing,
Huub