One of the main features of GTA V next gen is the possibility to, one single time, transfer your GTA Online account to the new gen consoles/game. VG247 wrote a guide on how to do it:
GTA 5 guide: how to transfer characters to PS4 and Xbox One in GTA Online | VG247
Remember though:
But it doesn't end here. No game launch without problems, and even the best shall suffer. The whole transferring of accounts seems to fail with profiles that haven't logged in since 2013:
Also, if you plan on heading straight into Online, brace yourself for impact of a sunlight-blocking 1.14 Gb patch. Only required for online play though, you won't have to worry about it immediately if you intend on playing offline first.
And to end with good news, did you know the revised GTA V soundtrack features 162 additional songs?