They occupy a lot of key terrain near the front. They also seem, ruble for ruble and man for man to be several times better than the MoD’s troops. If they simply melt away into the populace or are magic-wanded to Neverneverland, then Ukraine is suddenly on a roll and with momentum they’ll slam into the hapless MOD forces nearby the Wagner areas. Chaos will reign supreme on teh MoD side. Ukraine forces might make it to the Ukraine / Russia border in places.
That’s not war-winning for Ukraine, but that would be the biggest alteration in the terms of trade since, well … a long time ago.
That’s also an implausibly clean change. More realistically armed dudes used to a paycheck seldom quit the field quietly. If they aren’t paid by somebody, they’ll simply go local warlord in whichever direction offers the easiest pickings.
Which is probably more towards Russia proper, in Russian MOD- and Wagner- occupied far eastern Ukraine, than it is pushing towards / through Ukrainian forces.
Either way, Wagner falling to pieces is real bad news for the Russian state of play on Ukrainian territory.
At the same time, Wagner evaporating as a coherent force would probably be excellent for the stability of the government bureaucracy in Moscow. Which may or may not continue to include Putin at the helm.
We (the world) may be living through what may be the most dangers 36 hours since the Cuban Missile crisis. To be exceeded only by the 36 hours after that. Or not; this may fizzle rather quietly.