The light rail opposition is from the last bridge attempt. Vancouver proper has a different political landscape now and is thankfully ready to develop around transit, and Clark County is split but could be convinced.
A smaller-scale replacement on top of tolling both crossings and redirecting freight to I-205 could be enough if there's a separate light rail crossing. A congestion toll would work wonders for their traffic.
Oregon places a high priority on the Interstate Bridge Replacement, but Washington has a lot of other needs that we're throwing money at (finishing the SR 520 program, rebuilding Snoqualmie Pass, widening I-405, extending SR 509 and SR 167, ferry replacements, preparing for our own I-5 rebuild in the coming years...and this is all in the Seattle area).