Ultimately this will be a good move for RR. The sale of the IAE stake generates $1.5bn this year along with revenue of about £140m per annum from the business for the next 15 years. RR will still make money on the supply of spares for the engine along with assembling 50% of the engines....again for a fee most likely.
The v2500 as it stands will die out. RR has much bigger fish to fry at the moment with delivering the Trent XWB, Trent 1000 and managing a growing installed fleet. Having missed the NEO platform, it makes little sense for RR to maintain a stake in a JV that isn't dveloping new engines.
The JV with Pratts will be low key for several years during which RR can deliver the above programmes and PW can get on with the GTF. When the next gen narrow body comes round, both companies will have the resource and the capability to support a new product development. Had RR maintained it's stake in IAE, it would have ultimately lost out on the inherent value in the company and also allows RR to free up a significant sum to support future take overs, re-investment in the company or dividends to the shareholders.