i asked the HG route group manager the same qn @ the Eunos Int
coffee evening. he said that the cost of getting a model designed,
commissioned and mass produced is very very high and that SBST
isn't willing to spend that amount of money. moreover, our bus fan
base and hobby is not as widespread and prevalent as compared to
other countries like HK and the UK.
he said that the twin pack and the single model were specialy made
to commemorate SBST's 30th anniversary and renaming from SBS to
SBST. so highly unlikely that more models will come out.
as for TIBS, Corgi announced that they were looking into mass
producing the habit model (1:76) but seems that the plan has died
down. [SBS also wanted to mass produce the AN68 model but the plan
also dieded...]