As alluded to above, investment in good lenses is the go. For the most part, they are forwards and backwards compatible (especially the Canon & Nikon brands from my research) and unless DSLR architecture undergoes drastic changes (unlikely I reckon, in the foreseeable future), you will have and use them for life.

Bodies will continue to come & go, as already-developed DSLR technology is trickle-fed to the consumer.

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MY99 WRX sedan WRC blue Sold :(
MY99 WRX sedan Dark blue pearl :D
MY97 Liberty Outback Ltd Wagon
1990 Mk3 Supra turbo fully rebuilt 7M-GTE (Older son)
1991 Celica GT4 (Younger son)