We're just a few weeks away from knowing for sure, but news from Taiwan today suggests that Samsung will be using multiple types of processors for the different Galaxy S4 variants worldwide. According to the Taipei Times, investor group JP Morgan said in a note to clients
Similar to its previous Galaxy S3, Samsung is expected to adopt multiple solutions for the application processors and baseband chips in its new Galaxy S4, which will be unveiled in New York on March 14
If this is the case, we have to wonder if global units will have full LTE support. It stands to reason that Qualcomm's new gear will support LTE as well as their current offerings do, so maybe Samsung wants to provide the best experience possible while they work on LTE support in-house.
Right now, everything is just a rumor. We'll know more on March 14.
Source: Taipei Times