The scope is good and prospects depends upon your skill sets and ability to deliver typical solutions within a high schedule.
It depends on what you mean by luxurious!
All SAP consultants can earn well if they have skills and have dedication, adaptable and able to focus on the need of client's. There will always be demand for that skill set.
Why do we need SAP PI?
Apart from Legacy Systems, in a large business establishment, SAP ERP does not consist of a single system but several integrated systems i.e. CRM, SRM and FICO etc. To handle with such complexities SAP introduced Process Integration a platform to provide a single point of integration for all systems without touching existing complex network of legacy systems. This is a powerful middleware by SAP to provide seamless end to end integration between SAP and non-SAP applications inside and outside the corporate boundary. SAP PI supports B2B as well as A2A exchanges, supports synchronous and asynchronous message exchange and includes built in engine for designing and executing Integration Processes.