Dedicated busways have always been considered transitional between normal on-road limited-stop buses and some kind of rail transit. Unless the Orange Line is already running bumper-to-bumper, though, there's room to add capacity with buses. Lines that run local loops in the outskirts then jump on the busway for an express run to the subway terminal, for instance. Adaptive cruise control and "cab signals" to run more buses on shorter headways. Perhaps bigger buses (it's already using standard articulateds iirc), but there's a limit to that if the buses need to be able to use normal streets and freeways (is the Orange Line yard on the Orange Line itself so buses never have to leave it?).

If LA is going to the trouble to build viaducts at congested spots with rail-type stations for the busway, converting the whole mess to rail should probably be on the agenda (and build those bridges heavy enough for rail). There are other parts of town where rail will be more cost-effective in the short term, though, so making better use of the busway should also be on the agenda.