Mind if I ask what you are basing this on? Because the experience I'm having in my country tells me that would probably just reinforce the status quo, and then the far-right would have a huge increase.
In my country the center-"left" soc-dems (who have been leaning more and more liberal) were in power since 2014, with a majority on the left; in 2022 that party got a majority of votes, and the rest of the left loss a lot of votes, but the right was still in minority. This has essentially resulted in them being able to keep doing whatever they want and what they've always done and not keep their promises because they know a bunch of people always vote for them anyway because "it's them or the right wins!". Then in late 2023 there was a corruption scandal that resulted in us having new elections early this year where the far right saw unprecedented growth, the "center"-right party won the elections, and there is now a majority right in parliament. At no point during these 10 years did our country turn further left; the right certainly didn't.
My point is, based on that, I would guess that having liberals (who are the ones in charge of the Dems) in power so long with a majority would just result in them consolidating power, the rest of the left to be pushed out, and eventually for the far right to see a renewed growth.
The real solution would either be for everyone to vote for a new different left-wing party (if we're already talking about convincing "everyone" to vote for Dems, why not dream a little higher?), or turn to mutual aid and grassroots movements. And a party that wins elections will almost certainly never want to change the electoral system because they benefit from it the most; again, the best hope for that might be getting behind one party whose mission purpose is exactly to turn away from a 2 party system.
So fucking predictable.
Remember when Biden stepped down? Do you remember how unpopular he was and the massive wave of hope and support for Kamala that showed itself? Well, what the fuck did you think was gonna happen when Kamala glued herself to Biden, and tried to appeal to center right voters? They refuse to make compromises with the left, try to appeal to the center-right, and then blame the left for not voting for them; classic center/lib playbook, the same thing happens in Portugal, same thing happened in 2016 USA elections.
I thought that Democrats would win DESPITE the absolute dog shit campaign, given everything about Trump, but it was still an absolute dog shit campaign by people who claimed this was the most important election of people's lives, but then dug their hills in ideologically and refused to compromise with people on their left.
If the situation wasn't so dire, it would be hilarious to see the double think by Dem voters in this thread:
"How can Rep voters not hold Trump accountable despite everything he's done!"
"It's not the Dems fault that they lost, despite trying to appeal to the center-right instead of the left; it's never their fault! It's the leftists fault for not voting Dem! Kamala did nothing wrong!"