Fly ZB
You're right, the problem is what to do about it.
The historic layout of the terminal doesn't make sense and causes problems on the airfield with bottlenecks and the like.
Clearly things on a grand scale don't happen overnight - my own view is that in 10 years time a new T1 will be need to be on the ground and the time to start thinking about how that will happen is now.
It is a busy terminal but with the soon to happen expension of T2, with plenty of scope to expand further and the scope to expand T3, an opportunity will then exist to demolish T1 and fix all of the problems in one go.
Epic project though and will cost plenty. How to fund it is the question?