I usually scan everything but keep paper copies of anything that requires an original paper copy like wills, power of attorney, marriage & birth certificates, etc.
While I have the registration and insurance cards in my cars, I have an electronic copy on my iPhone and iPad. I also keep stuff in 1Password like insurance cards, credit cards, passports, drivers licenses.
If you go all in on paperless make sure you have a very good backup and disaster recovery plan in place. Testing your backup and recovery is also important.