I think the demise of the "traditional" tracked SPA is vastly
exaggerated.
Tracked SPGs are to provide arty support for Mechanised formations.
Wheeled Arty or Towed Arty are for motorised or legs infantry.
Still hasn't changed.
The recent spurt in R&D on light weight wheeled SPA has more to
do with the changed threat matrix of the major armies than on them
abandoning tracked turreted SPA for truck mounted guns.
With the demise of the Warsaw Pact, there is no longer a pressing
need for large numbers of MBTs and their attendent tracked SPA.
Instead, these countries now find their focus is on international
peace keeping duties with an emphasis on light, rapidly deployable
forces. Hence the sudden surge in interest in wheeled SPA (G6,
Caeser) and lightweight tracked SPA (eg. Soltam Rascal, KMW
AGM).
The only innovation I see is in the marrage of the towed Artillery
with the truck platform that used to tow it. This allows for higher
carraige speed both on and off-road as well as faster deployment
times. At the end of the day, it still remains an Artillery
platform for motorised or legs formation. Artillery support for a
mechanised formation will still require a tracked SPA platform. The
spate of new lightweight tracked SPA is more due to the need for a
platform to accompany the RDFs (which seem to be flavour of the
month for every army).
That doesn't mean that Heavy tracked SPAs are no longer required.
While the matrix for the old Warsaw/NATO threat axis has changed,
there are still plenty of potential "hotspots" worldwide where
large scale conventional warfare is still a possibility. In such
"hotspots", the respective armed forces are actively
acquiring/developing modern MBTs and tracked SPAs.
Examples of such hotspots include Greece/Turkey (the med equivalent
of Singapore/Malaysia). There is also the staple North/South Korea
"truce" as well as the India/Pakistan saber rattling.
Take for example India ... While India currently lacks a modern
tracked SPG, it is not for the lack of trying. The recently aborted
Bhim T-6 SPG was their attempt to indigenously develop a tracked
SPG. Instead, the Indian Defence Ministry has recently (May 07)
issued a RFP for approx. 100 tracked SPG platforms with likely
options for more to be produced locally with some form of tech
transfer. Other countries on the list of recent purchasers of
modern SPGs include Greece who have opted for the Pzh2000 along
with their Leo 2A6HEL. South Korea has the K-9 whilst Turkey has
the Firtina deriviative. Singapore of course has the SSPH.
So in conclusion, heavy tracked SPA in the classical mould have not
been dethroned by the upstart truck/gun hybrids. They both fulfill
different roles and it's just a matter of the local political
climate as to which will play the larger role.