journey11 said:
I'm gonna be the odd man out and suggest you give it a chance (unless you have your heart set on a red one). Maples are VERY hardy. They can take a lot more abuse than most other trees. This photo below shows how my neighbor likes to prune his maples. I've watched him chop down several over the years to 8' stumps and they send out new limbs very quickly. Within a year they are back to casting shade.
I'd prune out the damaged limb and if you want to, you could also cut the two remaining good limbs back to a foot or more in length and wait for it to fill back out. Couldn't hurt to try.
https://picasaweb.google.com/lh/photo/qME-72F3krBD55S3gFU1SWDLpkfXl8AyRU3YhBoAqLY?feat=directlink
That type of "pruning" is called topping and is very unhealthy for the tree.
Any new growth will be weak and prone to breakage in a storm, not too big a deal out in a pasture, but not so good near a house.
Giant wounds like that also make the tree hugely susceptible to disease.
In Europe they practice pollarding which
looks a bit like topping, but it is started when the trees are saplings in the nursery and is carried out yearly. A tree that has been pollarded correctly is maintained in that fashion yearly. The tree can't then be let to go back to grow out naturally or you would have the dangerous situation of weak attachments.
Certainly topping has been done lots of times and lots of places and it appears as though the tree is fine. But it's not.
I second the suggestion to get yourself a healthy tree with good
structure. A decent nursery would be pleased to help with that.
You may be able to prune the tree and it may come back, but eventually, judging by the diseased bark that appears to be running a good ways down the trunk, your tree will only be bigger and harder to remove if you let it remain and slowly decline.
Trees are a big investment, not just initially, but since they are so long lived, it really is worth it to get yourself a healthy one that will outlive you.