A big reason the Type 74 hung on is logistics:
http://www.kantei.go.jp/jp/singi/shi...i5/siryou1.pdf
Bridge Passage Rate in Japan based off of 17,920 bridges in Japan; extracted from that PDF via Google Translate:
Foreign MBT (60 tonnes): 40% of bridges in Japan (M1A2 and Challenger II, 62 tons; Merkava Mk 4, 65 tons)
Type 90 MBT (50 tonnes): 65% of bridges in Japan
Type 10 MBT (44 tonnes): 84% of bridges in Japan
Using Curve Expert Professional software, I estimated through various equations the passage % of the Type 74 -- many of them were in excess of 100%. A more reasonable estimate would be:
Type 74 MBT (38 tonnes): 90-95% -- taking into account that 83,775 lbs (38 tonnes) is still pretty heavy; many of the residential bridges I drive over as part of my work have a weight limit of around 38,000 lbs.
Also, for fun, here's what Pat mentioned:
Type 16 Maneuver Combat Vehicle (26 tonnes / 57,320 lbs) -- you can see why the Japanese are going for a Heavy Mobile Wheeled Tank system -- it'll be cheaper and faster to move around than even the Type 74 MBT.
Also highly likely is that new 105mm ammo will be developed for the Type 16 MCV to offset the smaller calibre main gun.