What are the buses unlikely to have their lifespans
extended?
You mean the next batch?
IMO, 1969A (BN 81), 1972P (BN 21), 2622T (BN SP, ex-BN
518).
2622T is almost confirmed de-reg early given they repainted
& refurbed all the way up till 2624M already (2624M's latest
repainted livery covers the former gloss-stickered one). Blue
seats, grey ducts for 2622T, plus high mileage from doing 518 all
this while its siblings like 2620Z & 1896B all left 518 way
before.
1969A is the same case as the non-extended 1960Z (like you
posted above). Both have yellow seats, but those were from the
IMF-era. 1969A's seat backs are disastrous since transferring from
BBDEP, always been the case. The painted seat backs are macham
brush-painted, some are grey, some are dark-blue. Plus 1969A still
grey A/C ducts as of what I know.
1972P that one might be possible early de-reg, but personally I
hope it's extended. Possible because somehow they never repaint
this bus but they repainted both 1973L & 1971S (1971S is
bumpers & roof only), but 1972P IIRC didn't even its bumpers
repainted, it's still in gloss-stickered form. The red A/C ducts
for 1972P are from years ago IIRC, one of the earliest Striders to
get refurbed red AC ducts.