The past couple of weeks I've been trying to get a FlyInside P3D Preview build out so that those backers don't need to jump in blind, which is why you've seen all of the P3D related e-mails. Now that this is done and the pressure is off, my focus will be back on FSX
If you look at the reward tier deadlines, you'll see that I've staggered Prepar3D so that I can focus on FSX first and meet all of the tier deadlines for it.
That said, when I work on FlyInside FSX, a lot of the code is shared. Some of the improvements I make for FlyInside FSX will ripple into Prepar3D, and vice-versa. If you are asking whether your money will go towards creating a great virtual flight experience for FSX, yes it will! On the other hand, all of the work I do on FlyInside FSX will also benefit FlyInside P3D due to the integrated nature of the two products, so I cannot promise that your pledge will not also benefit Prepar3D.