If this is your plan, then plan to never get a new phone.
Ok, maybe not never but its not going to slow down any time soon. This is just the nature of the beast when it comes to tech. And the more tech they can jam in a phone, the faster they are going to start coming out.
At some point you just have to take the step off the cliff and be happy with what you have until its upgrade time again and you take the step again.
That's not an issue in this case, since he has a DROID already. He has the option of waiting until 2011, when LTE would be more wide-spread. In that way, it's prudent to hold off on the Incredible for a better phone since he owns a DROID already. This argument of "plan to never get a new phone" only applies to idiots sitting on the fence with no device or much older smartphone hoping that there's something new and awesome on the horizon.
Be that as it may, the Incredible, as incredible as it is, is still nuts and guts of the Nexus One. So, aside from a better camera and software, you still have all the intrinsic weaknesses of the N1, e.g. screen resolution (not a true 800x480), screen touch insensitivity/inaccuracy, 3G antennae issues (may be mitigated by VZW's better coverage)... they went back to soft keys, and we know how those performed on the N1, screen glass fracturing (I just responded to a post re: the Desire, which mysteriously cracked like the N1), AMOLED... don't get me started on the inability to see it in direct sunlight, color inaccuracy, etc., especially when Super AMOLED is already out on some phones.
The Incredible is great in many ways, but so is the DROID and yet both are really crappy in other ways. Point is, if you have a DROID and can wait until 2011 for a new device, do it. No sense in picking up the Incredible. It's not even the best Android smartphone out there (HTC Evo4G). So what's the point? If he chooses to wait, there's no stigma attached to this decision, unlike if he were sitting on the fence with a RAZR or G1 in hand wanting to wait. In the latter situation, jump on a new phone now.
And as for the wife's upgrade... wait until the iPhone for VZW comes out. That's what I'm doing. That way you can have an Apple and an Android in the household. No sense in taking sides, just cover all the bases. One of each! Knowing my wife, she'd enjoy the easy nature of the iPhone over an Android device.