We've discussed this before.
1st thing to get out of the away, Online multiplayer behind a paywall on both XBLG & PS+ is Bullshyt. Steam has a better infrastructure than either XBL or PSN, without Valve using a paywall. I really hope SteamOS takes off, so it forces the console makers to drop their bullshyt online multiplayer paywall.
Now to answer y'all questions, The issues with PSN on PS3 are PS3 hardware issues (limited system RAM & outdated Wi-Fi chip). None of those issues are factors for the PS Vita & the PS4. If y'all are really so worried about PSN on PS4 (I don't think y'all are. It's obvious y'all trolling), y'all need to get your hands on a PS Vita for a week & compare PSN on PS Vita to PSN on PS3.
The PS Vita's Wi-Fi chip has the current standard 802.11n standard, unlike the PS3 which uses the outdated 802.11g standard. The PS Vita has more RAM to work with than either the PS3 or Xbox360:
So, no! I ain't worried about PSN on PS4. Also, Sony is moving PSN from
Amazon Web Services to
Rackspace's
Openstack. So, PSN will be running on a new cloud service.