You forgot the possibility of making 852 AM controlled ;).
From the proposed conversion of 178 to peak hour service and
shortening of 852 to AMDEP, it seems that SMRT is trying to free up
buses for WLDEP.
Beefing up of fleet or new service controlled by WLDEP? Anything is
possible.
And of course there's no need to have staff bus to AMDEP
already.