They've replaced those jobs *for ever*, not just for a single annual pay cycle.They can (and will, according to the article) scale it up too. IT won't cost *another* 48bil to replace the next 2600 jobs, and so on.
So 48B in development etc isn't just to save the costs of those 2600 jobs, they were just the jobs picked off first. Going forwards the cost/replaced job will be (relatively speaking) a few quid.