After 11 years of renovation. Satellite 5 will also open. This and South Wing are for UA and Star Alliance. That's what NRT officials are planning.

Just give you an idea if you are not familiar with NRT.

UA is currently using Terminal 1. The check-in area is North Wing. Half of T1 check-in area is currently closed, and this closed portion is South Wing. Currently, principal UA gate areas are Satellite 3 (Gates 30s) and Satellite 4 (Gate 40s).

If you arrive at Gate 40's and want to go through immigration, right now you have to walk all the way to get to North Wing. It is a long way walk, at least that's what I think. I think after South Wing opens, this walk will be cut down significantly.

A news release by NRT airport authority says South Wing and S5 will be used by Star Alliance including NH, UA, OZ and SQ. Domestic flights by NH will also move to South Wing.

http://www.naa.jp/jp/press/press050630_2.html
(news release dated June 30 in Japanese. I am sure they will prepare an English version soon.)

There are two links to pdf files. The second one shows the terminal map when all the satellites are opened.