The future pilot programme locks you into BA for 7 years.
No, not really. You can leave anytime you want. All that would happen is that BA would stop repaying you from your bond, which would then become forfeiture of that sum by way of your training costs for the approved course of ATPL training, and whatever airline flight experience you would have amassed up until that point.
The concept and intention, is that you are making a commitment to a career with British airways. This is viewed as a very desirable career within the industry generally, and the opportunity for cadets to embark on it is hopefully going to be viewed as a professional lifetime career commitment.
What happens to your £86k if the airline goes bust?
It is not "your 86k" it is a bond to cover your training costs, that is repaid to you in instalments as part of the scheme bonus, if you remain with the airline for the subsequent 7 years. This is the cost of your training. This is your bill. If you are succesful then you are rewarded with a career at BA, and as part of that reward, the (minus inflation) costs of the training course are returned to you over the next 84 months.
If you don't think the future is sufficiently guaranteed, or the scheme is too much of a risk, then simply don't apply to be considered for it.
Similar training can be sourced from the same schools in this scheme at similar cost, with other partner airlines, (who also will not provide any guarantees,) and may or may not repay the bond to you in staged payments depending on their own terms and conditions. Similarly you can do the training and find your own potential employers if you want.
Commercial pilot flight training isn't risk free. This scheme isn't risk free. It is a variation on a cadet scheme model that already exists with certain other airlines. Many view BA as a particularly attractive cadet employer. This is an opportunity to work for a First class airline, with good career prospects, and the possibility of financial help that might preclude a few applicants from similar schemes beyond the BA one.