Having Voldemort as the central pin holding everything together does open some potentially interesting threads you could do after his fall.

So maybe the "Light" had expected that with Voldemort's death, the entire movement would collapse, and they're kind of right, so long as it doesn't culminate in a big battle, but is snuffed out over time. The Death Eaters aren't any more, but that just means you've now got a few splinter groups running around:

The thuggish ones re-start the Knight of Walpurgis, who believe that they're in the right by crusading against impurity. They're much like the KKK, in that they tend to use physical and terror attacks to pressure muggleborns and race traitors to leave the community/country.

Greyback's dead, but his second in command is more of a political animal. They target the heirs of important families, and the last members of bloodlines, with the aim of infecting as many as possob;e - they're aiming to get restrictions on werewolves lightened, by causing fear that you too might become a wolf.

One of the recent Hogwarts' students, sick of the bloodshed, decides to start campaigning for bringing the muggleborn into 'civilized' society at a younger age; and to ensure that they're raised well and kept safe, so they can learn and understand more of their (future) adoptive culture. It appears to starts with good intentions, but those students who don't take part seem to have a very high fatality rate, normally in "gas explosions" or "freak tornados"; whilst those that do often state that they'd prefer the 'more progressive' views held on mainland Europe.

And nothing changes in the Wizengamot.

 

For me, the most interesting aspect of "linchpin Voldemort" is the opportunity it gives to explore each Death Eater as a force of their own. You can imagine a world without Voldemort where each of these dark wizards is themselves an mini Big Bad, feared in their own right and too independently-minded to even consider sharing power.

Lucius Malfoy, the organised crime boss, his fingers in every pie.

Bellatrix Lestrange, internationally feared wand-for-hire, a murderer without conscience.

Augustus Rookwood, a serial killer who performs sadistic magical experiments on his victims.

Travers, a corrupt politician with a prestigious name, looking to become Minister for Magic like his father before him.

Barty Crouch Jr, a powerful young Auror on the take, a sociopath behind a mask of dutiful filial piety.

By painting each Death Eater as someone who could have been a powerful, individual agent of dark magic, the Death Eaters become so much more than Voldemort's lackies. They're individuals, each with a rich character, goals and methods, who would never have worked together if not for the unifying force of a wizard so powerful that they had to take notice. Voldemort becomes more impressive by association - the unique man who could bring these powerful individuals together - and the Death Eaters as a collective are similarly much more interesting as a diverse group of individuals rather than a uniform pressure group designed to represent one side in a political system.