The PSD parts are unique and nothing like it exists on the market, AFAIK.

So, as far as I can see it, you have the following options:

• go for some of the smaller PSD devices, which is labelled Active in ST's product selector; however, it appears that only the 2kB and 8kB SRAM devices are available anymore (PSD834F2, for example). I'd guess you rely on the big SRAM otherwise you would select the smaller device straight away, wouldn't you...
  
• if replacement for only the RAM/FLASH combination memory is needed (i.e. you don't use the PLD part and I/O), go for some of the new MRAM/FRAM devices - of course that means also the low-address latch etc.
  
• try to have a look at the uPSD devices (specifically uPSD3354), which are in fact an 8051 (a 4-clock one in the case of uPSD33xx/uPSD34xx) plus almost unmodified PSD, all in one package

JW