If I'm correct that the spans of the Interstate Bridges are in decent shape and that it's the piers and supports that aren't braced against earthquakes, then when (if) the Interstate Bridges are replaced, Multnomah County should grab a few of the low spans from the state and barge them up the Willamette. The county could then recycle the spans to replace the Sellwood Bridge, which may be a lot cheaper than building an entirely new bridge. Though bridge spans don't compare with the fabled nine lives of cats, they do get re-used; if memory serves me rightly, the Vista Bridge replaced an older span that was moved south a few miles to serve for 60 years as the Terwilliger Bridge, and when the Terwilliger Bridge was replaced the old span was moved east of the Cascades, where it still serves traffic over some rugged canyon.
The Interstate Bridge could then become the Intrastate Bridge, an adjustment requiring a change of only two letters. Or the bridge could be identified, in its new location, as the Cesar Chavez Bridge, thus simultaneously renaming and relocating a portion of historic Interstate Avenue without changing anyone's address.