I'd like to see the Playstation and Playstation Portable become the same product with the PS4. The PSP2 (as we'll call it) could be a part of the PS4 and detatch for use away from the home and could also be used as an extra pad for the PS4. The PS4 could have a massive main memory (say a 4TB HDD) and you would then be able to download PS4 & PSP2 content to the PS4.
Then when you want to play on or watch the PSP2 you would transfer the content from the PS4 to the PSP2's internal memory (say 500gb flash memory) and take the device with you on the go.
Obviously we're talking maybe another 3 years down the line (hence the larger storage amounts than we currently enjoy as standard today).