It is not fire blight. An apple or pear tree will be infected with it on new, actively growing tips and move down the branches from there. The other branches look healthy. However, last years growth looks pretty active. Make sure and not apply too much nitrogen fertilizer on the tree or it can cause fire blight to attack. The more vigorous the tree the greater the chance for fire blight. I personally do not fertilize my in ground pear tree to limit the chance of fire blight. It would help to know what state you are from. It makes it easier to diagnosis a problem. If you are in a hot, humid environment the different color on the main trunk is probably just some kind of fungus. I live in SE Texas and we get many types of fungus that grows on trees. Most are harmless.

As vgkg has indicated, the entry points for fireblight are the flowers in the Spring, and the new growth later in the season. You might consider using Agri-Mycin (streptomycin for orchard use) on the flowers as these are the hardest to deal with once infected. I've nearly lost my 20th century Asian pear twice, but it came back both times after cutting it back to the main trunk. In 2 decades of growing Asian pears, I've had fireblight problems with several of my more than a dozen varieties, and haven't yet lost any, but it requires close monitoring and aggressive pruning out the affected branches at the earliest sign of disease. Some of my trees have never been affected even though they are varieties not known to be resistant and I really can't explain why but I'm not complaining. I've only had one European pear affected and that was a Comice which was damaged extensively just one time.

Yes blight very common in Bay Area I used to live in San Jose removed my pears because they always got blight so many other god options to grow in that area especially stone fruit

"Am I better off just cutting it down? and re-planting next year? or see what happens?" I'd trim off as much FB infected twigs, limbs, & branches as possible and see what happens. One of my Bartlett's was heavily infected about 4 years ago and after heavy pruning (including the dark colored bark/branches from the main trunk) it came back a-ok the following years. The last 2 years it gave me a bumper crops galore.Whenever a late frost/freeze kills the early blooms I will remove these dead bloom clusters asap as it seems to be the initial infection point of FB and it spreads rapidly from there down the limbs.