Luckily, from 2018 on, SNI will be mostly unnecessary, as LE will support Wildcard certificates, with DNS verification, for many domains in a single certificate.
SNI will still be necessary for when you have multiple servers under one IP (until IPv4 is deprecated, this is necessary), for example on a shared host (which might even have shared IPs under IPv6).
IIRC there are some ways SNI will be encrypted with TLS 1.3 so it's not a problem to begin with.
IIRC there are some ways SNI will be encrypted with TLS 1.3 so it's not a problem to begin with.