It's hard when you're RAGING.
In any case, clearly the solution to Portugal's problems is an event that fires in the mid 1500s that puts them under Castile/Spain in PU, and an event that frees them if Spain/Castile loses to the Dutch revolts. This should, in theory, put Portugal quite safely and soundly under the greater Spanish protection and likely leave them there since AI Castile never touches the low countries, resulting in general happiness for most and some abject forum-flurrying rage from BFTeixeira.
Or, meanwhile, we can realize that AI Portugal's inability to hold onto its empire has absolutely nothing to do with Seville as a trade node. It is due to Portugal's inferior position to Castile yet ready willingness to both join and go total war against them when called by an ally for any reason, by their inability to maintain a large fleet due to the all or nothing naval warfare mechanics combined with a lack of range limitation, causing them to take fights even in the Black or Baltic sea against opponents of no strategic importance against whom they are ALWAYS fighting a total war, and their deep longing and desire for Morocco.
No, let's ignore the actual reason for an empire built around scattered holdings and a need for peace and isolation on the side of a peninsula to frequently lose when their AI routinely suicides fleets, overcommits, or goes the distance against the bigger neighbor, and let's instead try to argue that the trade node being weakened would change the situation in ANY meaningful way.