I have stopped posting for a while, but this one got me hook, line and sinker.
I have to say, yes it is all possible, but it is being discussed in the latest pay negotiations as to whether the system is 'fair' or not. So may not be option much longer.
However you will find (certainly everyone I know in the position you describe) got into BA without even considering your little career path.
If your friend is honestly considering it as a path to BA, then he might want to start buying a lot of lottery tickets, he might be better off.
p.s.
Is the biggest IF I have ever seen.