I know it is not de rigeur in some circles, but to understand how to win, nationally, study Obama. He did it twice, and resoundingly. He is not a centrist, yet he pulled together a coalition that included them. He competed everywhere (like Beto in Texas). He is intelligent, charismatic, idealistic and pragmatic. Organization and vision are what won.
Many of the new Democrats follow that same pattern. They are charismatic, intelligent and organized (and diverse). They will make an impact, but they have to be pragmatic about it. That doesn't mean not being idealistic, but it does mean being strategic. Dumping Pelosi now is not strategic. Use her skills and experience, but learn from her. In a year or two, they'll be ready to take over. In the meantime, choose battles wisely. Focus on achievable goals - healthcare and infrastructure first, to make progress and show they can be effective. It means working with Republicans, but that's reality.
The reality is, they need to speak to rural America. Democrats have strongholds in urban centers, and growing influence in suburbs, but they won't gain and keep majorities without gaining influence in rural areas and States. FDR and LBJ managed that by providing principled vision. Obama made inroads. Clinton failed, not because of a lack of principles or intelligence, but because she couldn't sell her vision broadly enough. 3/5ths of the States are still rural. They need to be sold. Healthcare, education and infrastructure are programs they will get behind. Focus on those and Democrats will make inroads.
There are liberal values in rural America, they just don't recognize them as such. (See teachers in Kentucky and Oklahoma.) They need to be taught. 3 pillars that will have universal appeal: healthcare, education funding and infrastructure. Build community around that. It works in rural America and urban America. It's hope and change in different wrappings.