At Kirkham, NR are going to have to take at least one of the avoiding lines out of use, in order to build the new Up side platform before the line reopens after all the remodelling work.
Presumably they will build it on/near the formation of the current Up Fast line, with the current Down Fast becoming the new Up platform line.
As far as I can see, only the Airport fast omits Kirkham (except the odd one in the peaks), so it shouldn't be too hard to fit them in on the remaining lines until the new layout is ready.
The current layout seems pretty useless, with the avoiding lines reached via a 30mph crossover. They are still mostly jointed track too.