The fare structure for the Caribbean is also different from North Atlantic. The flight length is about the same, but the basic return fare is about twice as expensive - which might suggest that they intend to make money on leisure, rather than business.
I don't think there is any evidence that bmi intends to leave the North American business market - although it continues to juggle around to optimise the income from it.
I agree that yields and profits are down on shorthaul - hardly an insightful comment - that's obvious from the "profits" that have been declared in the last few years! However, costs are also being reduced (not least by going to single fleet from LHR) to match. And although the shorthaul product is now cheaper than it used to be, it is very definitely not low-cost. They still provide free food and drink appropriate to the flight and time of day; they still provide allocated seats; they still provide a newspaper - even in economy (okay, so what - it's pence - but it's service!); they still provide a flight connection service and support - which is the really big thing that locos won't ever offer; they have a service standards guarantee which is detailed on their website. You can still pay for a separate business class (or, more normally, the taxpayer can) if allowed by your employer's policy!
Of course you pay for what you get - but the point is that for only a few pounds more than the lowest cost of a loco flight, you could be flying from LHR (which against all reason is the preferred international airport in the UK!) with a non-low-cost service with pretty much all the bits and pieces that full service always had. And (see
www.spotfare.com [once it is running!]) - if you need to travel tomorrow, you can probably get a seat on bmi for less than you would have to pay on easyjet on the same route.