Are these trees about to die?

They look like my neighbor's spruce which has only gotton worse and worse every year. Now it looks to have spread to his other spruce. The tree started going downhill soon after our street was paved.

(His are badly placed trees to begin with, huge, in a small front yard, with power lines in front of them. I'm sure the cost of removing them would be too much for him, as a retiree.)

Something similar happened to the spruce trees at the local elementary school when they expanded the nearby parking lot.

May I hazard a guess that that nice blacktop running along the line of trees was fairly recently done?

Yes, I'm guessing that blacktop is no more than two years old.

This is on a property I'm interested in buying and those trees are a big part of its appeal.

I think you've put your finger on it - here's an article I just found describing exactly what you're talking about, and it seems to be the case with these trees:

The pavement was installed long after those trees were -planted and is preventing water and air from reaching the roots... you can see where the lower branches were removed and where the construction machinery has scarred the bark. Those trees are slowly dying, they should be removed before they fall.