Collocations for viable - adj.

be, prove, seem
None of the projects proved financially viable.

become
remain
make sth
It is only their investment that makes the project economically viable.

consider sth, regard sth as

extremely (esp. AmE), truly
perfectly
a perfectly viable form of political organization

potentially
still
no longer
commercially, economically, financially, politically

Viable is used with these nouns:
alternative, business, candidate, future, option, proposition, solution, strategy, system