i asked that at the interviews i did. most make partner. there are few who don't.
the practice i'm joining is a bit "top heavy", meaning that they have more than a few (read that: several) partners who are going to be retiring in the next 5-10. i expect that i'm going to work pretty hard the first couple of years, but that the prospects are good if i stick around. they are hiring two this year, and i'm one of them. they hired 5 in the last 6 years, and 4 of the 5 made partner. the fifth is still around and will be partner eligible at the end of this year. so, we'll see.