We know the LFA is registered in Ingolstadt, Germany, because of the number plates. That means Audi lent the car to its Italian relatives and were somehow also involved with the project.
Because of the way Lamborghini works as a company, we wouldn't expect them to launch a new engine any time soon. The Huracan has just been launched and what you see is what you get for the next seven or eight years, with small variations, of course. As for the Aventador, its V12 is the first all-new mill of this kind in many decades. So we expect even the next supercar that comes after it to use the 6.5-liter.
That just leaves a few models that have nothing to do with the standard Lamborghini modus operandi. The most important is obviously the Urus SUV, which has been confirmed for a 2017 debut.
Most SUVs sound kind of boring or artificially powerful in the case of performance models. One excellent counterexample is the Infiniti FX (now called QX70), which everybody around the office seems to love.
Maybe Lamborghini bosses had a round table discussion, and somebody said, "Let's make the Urus sound like that Infiniti." Ideas fly, and another guy says, "Let's use the Lexus LFA as a benchmark, it sounds different to the Huracan but still has a V10." And here we are!