NPM 7 is out and it supports workspaces. they will also continue to develop this domain in the upcoming releases,
With that said, lerna comes with many more high level features than npm7 or yarn workspaces, furthermore, yarn declared that they will never try to replace tools like lerna, rather they intend to implement the core logic of handling workspaces like installing children packages dependencies and packages symlink. I expect npm to do the same.
One great example is the command: lerna changed which gives you the list of packages that have changed since the last tagged release, this could be extremely helpful for CI/CD. you are welcome to explore the extra commands provided by lerna.
The only command as of today supported by npm7 related to workspaces is actually npm i / npm ci which is not new, but it does take care of nested packages and symlink.
I’ve written an article that goes deeper into the configuration in case you want to move to a monorepo with npm7, so working without lerna is definitely an option, you will probably need to do more work on the CI/CD side compared to lerna and add some dev scripts by your self that will affect the nested packages. Also IMO lerna fits more to develop libs rather than apps.