wrote:
About 10 years ago my neighbor planted two rows (staggered) of
evergreens to act as a privacy barrier.

Now the trees are getting pretty big and he is concerned that they
might choke each other out and die. �He could remove one of the rows
but the "insides" of the trees don't have any healthy growth since not
much light gets in there.

Questions a

- Is it possible that the trees could choke each other out or can they
survive close to each other?

They will survive quite well, that's how conifers grow in a forest,
they need only their upermost portion in the sun.... you can plant a
privacy screen/windbreak or specimen plantings, you cannot have the
same trees accomplish both.

- If he does remove a row will the previously unexposed side of the
tree generate new growth or will the just look nasty forever.

Nasty forever.