  SU(5) $\otimes$ SU(5) provides a minimal grand unification scheme for
fermions and gauge forces if there are vector-like quarks and leptons in
nature. We explore the gauge coupling unification in a non-supersymmetric model
of this type, and study its implications for proton decay. The properties of
vector-like quarks and intermediate scales that emerge from coupling
unification play a central role in suppressing proton decay. We find that in
this model, the familiar decay mode $p \to e^+ \pi^0$ may have a partial
lifetime within the reach of currently planned experiments.
