Whenever I hear people talking about Vueling replacing BA on short haul I think that a lot of people have forgotten the amount of trimming BA has already done to its short haul model and the steps that competing legacy carriers have taken.
Many forget that it was BA who made wholesale changes in the first decade of this century, long before Lufthansa, Air France et al did. BA closed its entire regional operation, both at mainline and at BA Citiexpress/Connect. The airline now only really concentrates on its core London market. They are not going to dilute their brand at Heathrow and I very much doubt they will at Gatwick either.
Look at Lufthansa, they have followed BA's lead, albeit taking a slightly different direction. They have cut their short haul branded flights from all but Munich and Frankfurt. Elsewhere it is now Germanwings/Eurowings that operate their short haul services. However, they have retained their core brand in their primary markets because they realise it would do more damage than good for the flag carrier to withdraw from short haul in their main hubs.
Air France have done the same, retreating from the regions and introducing Hop, but ultimately maintaining their core brand in Paris.
Rather than following the crowd via Vueling, I would argue that BA actually led the way with the 'Future Size and Shape' programme under Rod Eddington after 9/11. BA cut the majority of the fat from the regions retreating to Fortress Heathrow.
With the recent cost savings and increased labour productivity in short haul, BA are making record profits. A core short haul product has to remain to feed our long haul services. A huge number of our passengers are merely transferring at Heathrow to/from other European cities. We are expanding short haul, in the few months that I've been here we've already announced a variety of new routes, most recently Inverness.
BA may not be the Mecca it once was. You will fly 80+ hours a month, but it's got a solid future and many varied options for your career.