Perhaps Delta is also seeking a piece of Virgin America (A320 operator) as a part of the deal. Regardless, Delta seem to have big pockets and good strategy (like buying an oil refinery in Pennsylvania to reduce oil price volatility for NY area hub) - Virgin could certainly use both these days...
Not sure how VS pilot jobs could be impacted if this comes to fruition... Doubt Delta would want to squander the value of the LHR slots.