I'm afraid I can say with some reliable knowledge of the landowner and their plans, it's not a matter of "if", but "when" it gets developed.
Yes, it's a shame, but it's business. A non-flying landowner doesn't understand our passion for aviation, so it all comes down to return on capital. A £10 landing fee and a couple of sold pesto paninis aren't going to get them all excited are they? It's no different to horse paddocks that get developed. The jodhpur-clad chicks get all hot and bothered, scream and shout a bit, and then quietly load up their horses and find somewhere else to go.
As I've said before, GA in the UK has gone bonkers and rather awry in the last 15 - 20 years. It's been knackered by over regulation and people expecting to learn, fly, and pay for upkeep on a shoestring budget. All these things combined will have meant that Kemble (as with lots of other airfields) have a ROCE of a fraction of what they should do, and quite understandably are looking to become a part of the local development plan.
As I said, I don't like it, but it's happening.