X bottom line will be significantly hurt when Walmart resorts to utilizing there own infrastructure and trucking resources to deliver there own packages. Two of my trucks would lose 30% of there volume if walmart did this. Just imagine what X loss would be.
Walmart will do it, they have no choice. X will lose market share, ups not as much.
Amazon is redefining the shopping experience, bringing the store to your door. The last mile element to amazon is only one piece of its model, for X it is the only piece to theirs. Walmart will deploy a carrier element to their model also, and will succeed.
Both Amazon and Walmart will leave the scraps, unprofitable deliveries, to X and ups.
If you say they cant make it happen, well I say you are ignoring all the factors that are forcing them to do it. In the short term, X will bargain for cost to win accounts, this will be short lived. Welcome to the new world of ecommerce and delivery, one and the same. X didn't see this coming 5 years ago, or they failed to respond.