But then of course there's the problem that the new power would be weak, have no pre-existing support base (unless perhaps they were a long-established character like Hadrian), and would therefore probably be the next on the chopping block.
There also needs to be a way for successful powers to "win" Powerplay and be removed to make room for a new one that way.
So ... Mahon is declared the winner of Powerplay. Their Powerplay effects then apply permanently to all stations in their control/exploit zone at the time, the cooking laser becomes permanently available in outfitting in those systems, there's some big reward given to Mahon pledges based on their length of service (maybe they get to keep the rank benefits too?) ... and Mahon disappears from powerplay and is replaced by a few new powers - maybe two alliance and an independent CEO - and there's suddenly a load of space and a really large number of supporters free to shake up the dynamics a lot. And Mahon of course continues as a major plot figure - and even if the plot later has them killed, their historic influence on the Alliance will remain.
Over time this would degenericise the systems in a mechanically significant way - this system was built up into a trade powerhouse by Mahon, then succumbed to Kumo-backed criminality, and is currently being turned into a hydroponics centre by Senator Cornelius
Tangentially, I hate the whole "sphere of influence" thing where you create a "control system" and then you exploit everything within a, what, 20Ly radius?
I'd rather see it roll for powers to fill "roles" like they currently do... where Patreus is, essentially, the naval "force du jour" for the Empire, then the (NPC) representative of a faction who has (some measure of biggest military force) would ascend to that role. Likewise Torval would be the (NPC) representative of a faction who has the largest economic wealth, industrial, political, tourism, whatever. Or maybe periodically the top ten factions in each category go into some form of cg-like competition for the title... with the titles also conferring particular benefits. A faction couldn't hold more than one role, and has a cooldown when they lose a role. Of course, the major lore characters could still sit over the top... and you could even look at a mechanic where you could have multiple factions in each role; perhaps several factional leaders could elevate to power status as "Senators" within the Empire?
The other part is that the limited number of roles would encourage diversity and
prevent discourage whitewashing. So yes, say a group turns the galaxy Alliance-green... , but you'd still get Imperial factions sitting in Imperial Power roles, no matter how weak they are by contrast, and for player groups that would be the easier path.
I dunno... I'm rambling a bit, but I hate current powerplay mechanics.