When we see dark clouds, because of the situation now, we must say:
It's going to rain. Not It will rain.
Or when we see somebody is going toward the wall and can't see the wall in front of him, because of the situation now, we must say:
He is going to walk into the wall. Not He will.
Now, when we see shoes which are very well made, can we suppose this situation as a situation now-because we can see and get that these shoes are very well made- and say so:
These shoes are very well made. They are going to last a long time.
These shoes are very well made. They will last a long time.
Raymond Murphy has used will in his book.