Truth is ps2 did update. Its called a ps3.
That's not an upgrade or update. That's a new device.

And current model PS3s are not backwards compatable (The backwards compatability was done by literally building the ps2 into it- the Ps2 processor and such- it's not emulated or performed by the PS3 hardware; They eliminated the PS2 hardware to cut costs and lower the price of the PS3)