It seems like many people have been seeing 8 28 31 as destination buses instead of where they pass through. Terminating at Toa Payoh & Tampines isnt a bad idea.
Moreover 28 & 31 is a long route already, both of them bypassing places like Bartley, Paya Lebar, Geylang Serai, Bendemeer Rd, Old Airport Estate & Marine Parade.
28 connects the following places:

Toa Payoh & Bartley

Toa Payoh & Upp Paya Lebar

Toa Payoh & Geylang Serai

Bartley & Geylang Serai

Bartley & Bedok

Bartley & Tampines

Upp Paya Lebar & Bedok

Upp Paya Lebar & Tampines

Geylang Serai & Tampines East

Geylang Serai & Bedok (I know there's 2 7 26 30 for this)

Within Tampines
31 connects the following places:

Toa Payoh & Bendemeer

Toa Payoh & Kallang

Toa Payoh & Old Airport Estate

Toa Payoh & Tg Katong

Toa Payoh & Marine Parade

Bendemeer & Kallang

Bendemeer & Old Airport Estate

Bendemeer & Tg Katong

Bendemeer & Marine Parade

Bendemeer & Bedok

Kallang & Old Airport Estate

Kallang & Tg Katong

Kallang & Marine Parade

Kallang & Bedok

Old Airport Estate & Marine Parade

Old Airport Estate & Bedok

Old Airport Estate & Tampines

Tg Katong & Bedok

Tg Katong & Tampines

Marine Parade & Bedok

Marine Parade & Tampines
It'd be possible if Svc 8 could be extended, but does the demand requires it to? For the moment, I don't think so. If Svc 8 were to terminate at Bishan by bypassing TPY Int, it'd bring alot of inconvenience to people at TPY Central going towards Bedok Reservoir & Ubi. Hence, I'd prefer Svc 8 to stay as it is.
