Else doesn't sound archaic to my ears.
"When you go shopping make sure to buy flour or else we won't be able to bake the cake"
"otherwise" is a more common word choice but "else" is definitely in the active vocabulary of modern English speakers.
"When you go shopping make sure to buy flour or else we won't be able to bake the cake"
"otherwise" is a more common word choice but "else" is definitely in the active vocabulary of modern English speakers.
> When you go shopping make sure to buy flour, or we won't be able to bake the cake.
> When you go shopping make sure to buy flour, else we won't be able to bake the cake.
EDIT: TIL: Dictionaries don't commonly define "else" as a conjunction, except for Wiktionary. Still sounds natural to my ears, so this is a surprise.
> Make sure to buy flour, and we'll be able to bake the cake.
> Make sure to buy flour, so we'll be able to bake the cake.
> Make sure to buy flour, and so we'll be able to bake the cake.