https://www.ign.com/articles/playstation-store-shut-down-ps3-vita-psp
PS3 and P to shutdown on July 2; Vita on August 27th.
If there are any PSP, 3, or Vita games or DLC that you haven't gotten yet, now would be a good time.
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UPDATE:
The PS3 and Vita stores will remain open. It's currently unknown whether PSP games will still be available for download on the Vita, but I'd go for it anyway, just to be safe.