I am new to the concepts of UICC and Javacards so this question might not be coherently structured.
Anyways, i was just wondering if it is possible for a UICC to store multiple USIM communication profiles, one of which is enabled (recognized by the device and used for communication).
If so, what is the theory behind alternating between the profiles?
Yes, totally possible. I would even say that it is probably the best way to do it.
USIM profiles can be considered as Javacard "applications" and be downloaded, installed, switched on and off or deleted as the device owner decides to switch mobile operator. All this operations can be implemented using the GlobalPlatform security architecture (Security Domains, delegation modes, etc) enabling different roles: UICC manager, operator providing connectivity, device manufacturer, etc. It can get as complex as you need.
This is especially interesting for machine-to-machine use cases. In fact, it is being hotly discussed in telecom standardization fora (ETSI, 3GPP, GSMA, you name it).
I realize this is not a programming question but I think it is worth answering because it is a very promising application for smart card technology.