Does it really mean that a theory can't be found or just like with "everything else", we can only be 99.99999999% sure and never reach 100%? Does it necessarily

Does it really mean that a theory can't be found or just like with "everything else", we can only be 99.99999999% sure and never reach 100%? Does it necessarily mean that the imcompleteness theorem extends to all systems? The article linked somewhere else in this thread: http://www.ams.org/notices/200604/fea-franzen.pdf http://www.ams.org/notices/200604/fea-franzen.pdf seems to say that it doesn't extend to other "systems".