Ya they planned a new 6 lane bridge and actually built a approach ramp for it during the Detroit side interchange reconstructions in the 2000s. That ended up being all for show and a stall tactic they used to propagate Gordie wasn't needed as they were going to build a new span.
Around 2020 or so Canada gave them clearance to build a new bridge to the side if they wanted to. Not sure what the US stance is but judging that approach is there they should be good to go?
They'll probably do nothing until maybe a year or two after Gordie Howe opens. Then it comes time, based on the traffic/revenue levels, to decide to build a replacement span. Either tear down the old bridge and building a new one, or build one parallel. They could also just choose to refurbish the current span (easier to do with less traffic) or just simply run it into the ground, performing as little basic maintenance as possible.
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You can see the (possible future) bridge connection on the US side:
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