This is still only the temporary Starbucks. However, I wouldn't be surprised if one gets built in Main Future World and then one in World Showcase, possibly very close to the Skyliner as you are suggesting.
Although, you have to remember that Joffrey's has a coffee agreement with Disney too and I think Joffrey's has World Showcase and Starbucks has Future World. Although that doesn't stop Starbucks from opening shop at the International Gateway.
Yes, they are at some point, but it hasn't been confirmed when.