It shouldn't be too difficult if there are designated bus bays
(or just a regular bus stop?) for the existing bus serivces (like
the underground ones in Terminals 1,2,3) right outside Terminal 4,
and a direct exit to PIE/ECP from Terminal 4 - that way the buses
would all do T3>T1>T2>T4 (skipping the existing bus stop
right before the slip road to PIE) before heading out.
Given how T4 was not meant to be a "budget terminal" (otherwise
why tear down the old terminal?) it is likely that public buses
would directly serve it, unlike previously when travellers have to
walk 5-10 mins from the bus stop along Airport Blvd to/fro the
Budget Terminal ...
Having DD- or bendy-friendy stops at T4 wouldn't solve the
problem of HCs not being able to serve T1/2/3, as it would just
transfer the crowding to the T2/4 shuttle bus...
Still support the idea of having "shuttle express" services from
designated MRT stations for now.