Pump supplies are funded by the NHS and they are more expensive than injections.
Therefore, any pump expenses need to be justified.
So, sure, there is a "possibility" you may be told to go back to injections.
However, if you can justify the value the pump gives you and, if you have just had a new one, the NHS will not have to fund the pump itself for 4 years, in my opinion, the chances of you losing your pump will be rare. That does not mean you should not be ready for a bit of a battle against some British bureaucracy.