I mean you can still develop and publish your APKs online but not being on the Play Store is enough to kill most apps.
I mean if you're so popular/useful that users will seek you out independently you might be okay but there are a lot of shops where the store is their only marketing funnel.
I mean if you're so popular/useful that users will seek you out independently you might be okay but there are a lot of shops where the store is their only marketing funnel.