You will not be selected in future Saskatchewan draws if you do not have ECA.
And you can create EOI without an Express Entry profile. This is called OID stream.
However, if you can create an Express Entry account, I strongly recommend to do it. This will direct you to SINP-EE stream which has way faster federal process.
OID (Occupation in-Demand) takes 17 months in federal process, however SINP-EE takes only 6 months.
Worth to note that OID applications are processed a few weeks faster than SINP-EE in provincial process, However, adding the time needed to process them both in federal, OID is about one year slower overall!