There are no grounds to cancel visas unless you are made redundant. If you’ve got over the 7 yrs then you are safe in that respect but it still doesn’t mean that you won’t be made redundant.
Some pilots have got Quality Migrant Visas which are for six years and they are also safe from the visa point of view. The company themselves have never suggested this as an option but a few people have done it after having heard about it from colleagues.