Powerplay is currently a system with lots of potential, however in it's current state, it falls flat. It essentially boils down to doing the same things you do outside of powerplay, but you get merit instead if credits. Basically the only reason to do it is to support a power you like, or for the special rewards.
Lets be honest, Powerplay looks like it was designed for this in the first place: Make Powerplay Open-only! This means that only players playing in Open can affect the Powerplay system. Why? With Open-only, Powerplay goes from being another background system, to something that takes place visibly in the galaxy! Imagine players trying to undermine a system, so the defending players set up a "blockade" to stop them. Naturally occurring PvP conflicts with an actual purpose can exist now!
Which brings up a happy side effect of this solution: less ganking. Really? Yes! You see, imagine your favorite part of the game is PvP combat; fighting AI just doesn't do it for you anymore, you want the thrill of fighting real players! So where do you find those fights? As it is, the only PvP conflict is Gankers Vs Anti-Gankers. Often, the same people play both sides depending on the night, because they're really just looking for attention to fight people. Making Powerplay the de facto PvP area provides an actual reason for PvP, and an outlet for those players, which doesn't currently exist within the game.
Even though they cannot affect the outcome of Powerplay, Solo players would still be able to earn merit, ranks, and rewards, including the special modules, for doing Powerplay activities.
Ultimately, Powerplay becomes the domain for PvPers to effect the galaxy, while Solo/non-PvPers still have minor factions to effect the galaxy. Maybe Powerplay is more significant in that regard, however this is balanced by the inherent risk that would be involved in Powerplay if these changes happened.
Being able to block players and never see them is a thing. So to fix that, how about just having that not be a thing if you're pledged to a power? I can't think of any other open pvp games where you're allowed to just not encounter a specific player, especially when Solo and Private is already an option… :/ Hiding chat messages should suffice for players pledged to a power.
The other challenge is players on different platforms, but that's not as bad as hiding in Solo or private groups because at least players on those platforms could counter them. Ideally crossplay would be best, but I won't hold my breath for that.
I think these changes would be relatively easy to make and would result in more interesting immersive content, the first real reason for PvP, and even provide endgame content, while still giving Solo players the ability to earn powerplay rewards, as this seemed to be the main complaint of these players last time I saw this topic come up a few years ago. Did I miss something? Am I wrong? I'm curious to hear other thoughts on the topic, specifically on how this could work while keeping the different types of players happy.