117 should have been introduced full fleet SD and gradually as
loading improves they could have done SD->DD upgrade.
I still believe 117 route is good and there is potential in
future, just not yet.
I see not much potential on this route, at least for the next
3-4 years.
New HDBs[By 2017] are built slightly further
from the route. If a new svc, A, were to run within the HDB, making
a transfer will be troublesome. Imagine crossing over to take 117
to Punggol, and crossing over to take svcA into Canberra
way.
Only those leaving near the route might consider.[By
2019] But you have a MRT station and what Punggol Waterway
point offers?
If the new svc were to terminate at Yishun, it makes
transferring easier(via 965). Unless they are going to Punggol,
85/965/969 may have better attractions than 117. Similarly to those
working at Seletar. Transferring to 103 and 117(if 103 have high
demands @ Yishun) might be a better option(in terms of
convenience).
At most a few DDs as split...that's all I would say.