It might last a loooong time, be one of the smoooothest rides built. Because frames are tensile and structures, the flexes\strengths have to be all worked out. A bike frame rigid in the wrong place can snap or feel awful.
Really nice frames have a lot of different tube shapes\butts\diameters\bends\ovals\struts\lugs\fillets.

Competent welding has a major factor in any tubing of ferrous nature.
Alu is best used in ways that do not promote flex.

A bike 'frame' can be set up with a very simple gear system!
The frame will still be the 'unchangeable' feature of the ride.
Simple or no...a good set of pipes rocks. If good, fits right =spend, if not, save for a frame.