Global Triumph

Yes, Cerato will likely take years to complete.

However, there's nothing preventing me from switching from Beta and just keeping the existing world active.

cant wait to see how long it takes

Baring any hick-ups simple match puts GDI at done under a year.  However taking into account resistance and good ole fashioned logistics issues I would for see it being closer to 14 months.

Just a guess.

For the record this is just math for the purpose of discussion and getting a realistic idea of timeline.
This doesn't imply a challenge or statement of global domination.

i can fight back, you know.

if you fought back / all alliances banned this map wouldn't be manageable.  As it is know it takes multiple hours a day to fight/expand.  This you know all to well.