It's pointless to speculate about counterfactual situations. Wishing can't change anything.
SOURCE: Matisoff, Blessings, Curses, Hopes, and Fears. Variations:
.ווען די באָבע זאָל האָבן אייער, װאָלט זי געװען אַ זײדע
Ven di bobe zol hobn eyer, volt zi geven a zeyde.
If grandma had balls, she would be a grandpa.
SOURCE: Furman, Yidishe Shprikhverter un Rednsartn
.ווען די באָבע וואָלט געהאַט אַ באָרד וואָלט זי געדאַוונט פֿאַרן עמוד
Ven di bobe volt gehat a bord, volt zi gedavnt farn omed.
If grandma had a beard, she would stand at the bima and daven.
Literal translation: If grandma had a beard, she would daven at the cantor's pulpit.
SOURCE: Stutchkoff, Der Oytser fun der Yidisher Shprakh