I wouldn't call it sustainable, but Subaru can persist for quite a while without an EV platform. Their main markets are the US (72%) and Japan (11%), neither of which have significant EV penetration. They are, and will continue to be, a bit player worldwide.

EV development also gets easier every year as it becomes more common. Companies don't have to have cutting-edge technology to compete, and Subaru has plans to release their own EV platform in 2029. I do not expect it to be cutting edge, but loyal Subaru owners won't be expecting that either.