Oh wow, when this thread did become a Powerplay mechanics thread? :O
Anyway, there's something I need to say as always: people still confound "PvP" with "Open Only".
"PvP" is often associated with the "duel" PvP mechanic, while the beauty of "Open Only" is the thrill that makes you (for example) think and strategize in supercruise, or makes you try to elaborate an alternate ship build to just hit hard and fast traders hauling powerplay commodities and evade combat against bigger (but slower) ships.
The human factor is the best way to gain variability in an otherwise far less variable game.
This said, I think that Powerplay issues are far beyond the Open/Solo/gGroup debate.
I think that right now what keeps people afar of Powerplay is how poorly it is integrated with the other game mechanics, especially the new gameplay.
We need a decentralized, overhead free, powerplay-flavoured mission centered Powerplay, with Powerplay missions covering as many game mechanics they can (from combat, to hauling, to exploration... of course according to any Power context and lore (for example, obviously Torval should offer mostly mining-themed missions, but they could be like "killing pirates to protect miners" missions too for example).
Right now being an active Powerplayer means necessairly ignoring most of the game to kill dumb NPCs, haul commodities and nothing else. THAT is what keeps people away from Powerplay mostly.
Then the Open Only factor could be a variability factor, what makes it different from BGS (for example).
And it's a damn shame, the sorry state Powerplay is in. Powerplay could be one of the main features of the game, it's basically the best way to have a feeling of "membership" in the game.
Let's just hope that Thargoid War mechanics will be moved to Powerplay too soon. Not very confident about that honestly, FDev never showed nothing but superficial interest on the matter.