As Matt H. said, La Cage has been running quite a long time. It opened in December. It's been running far too long for any replacement to even be considered. The whole Larry Kert/Dean Jones thing was a special circumstance that was dealt with by the Tony committee. Hal Prince discusses the whole issue in his book. I think, though I may be mistaken, Craig Zadan writes about it also in Sondheim and Company.
At this point, Robert Goulet is a replacement in a (somewhat) long running show. Gary Beach will most likely be nominated. I don't know about Davis. Certainly, I don't think anyone else in the show will be nominated. If Davis had stayed with the show, I think he would have been nominated, even if he wasn't getting along with his co-star. Those are my thoughts on the matter. Now I must run away for a few minutes and try to come back by 8:30 for a few minutes in chat.
Those of you who have never chatted before, get your typing fingers ready. It can get fast and furious in there ;-)