The russian military absolutely will develop counters that even the power imbalance some, I think Ukrainian military officials have said they forecast Ukraine has about 6 months of this general status quo to take advantage of.

While this is true, there are material, industrial differences that have swung in Ukraine's favor that will not swing back in russia's favor.

1. Ukraine's 155mm artillery production of howitzers and ammunition is one of the largest per month in the world, this was not true a couple of years ago, this fundamentally changes the calculus in Ukraine's favor.

2. Russia's aviation industry is for the most part in general collapse and decay.

3. Russia has already sent everybody who was valuable to die on the frontlines, they just don't have that many skilled personnel with actual experience left alive.

4. Ukraine's drone production outpaces russia.

5. Ukraine can actually protect its armored vehicle crews and infantry alive, russia cannot figure out how, this creates an ever snowballing disparity in skill in favor of Ukraine.

Russia will not have a choice.

It does not matter how russia feels about it, when you have been cut off in a combined arms operation that shatters your backline and logistics supply lines, the only choices left are to surrender or die like a fish in a barrel with no hope of escape. Those are your choices.

That is why maneuver warfare works, cutting off an enemy from their supply lines and suppressing them thoroughly from the air and with artillery creates the conditions where large amounts of enemy forces are forced to surrender without having to do battle with each and every enemy soldier.

It is something that always happens faster and more decisively than you expect it to, it is like glass shattering. You won't be able to see the possibility of it as anything other than a unified impervious system until it has already been shattered.

I think isolating and then forcing russia to abandon or essentially abandon Crimea is no less than a decisive demonstration russia has lost the war.

In otherwords, it is a strategic goal in of itself. You don't need to extrapolate out what the impact is, it functions as the end credits to the movie.

The "movie" ending here being the current open large scale land war, not an end to conflict with russia of course.

There is military wisdom to keeping some bridges of retreat open however, leaving the enemy a route to flee can be the knife in the heart of their will to fight to the last man. I can't really judge that calculus not knowing all the details of whether it is a good idea to completely take the bridge down or not.

To me it seems wisest though for Ukraine to set the explosives and leave russians an impossible choice when the time comes over whether to use a bridge that appears to so far have been impervious to Ukrainian attack or at least Ukraine has been unwilling to attack, or whether to try a much more difficult route of evacuation.