If he didn't leave for Argentina before joining Sevilla, which is his long awaiting dream, he won't ever leave for any other club before establishing himself first or win something important. One thing I learned about Sampaoli during his stay here, the guy is very intelligent and doesn't make stupid decisions in overall.
What if he fails at Barca? You guys along with everyone else will be wanting him out and he'll probably have to settle for a medium team or go back to South America. I can guarantee you that he will stay at least for another season at Sevilla, meanwhile, you better get Koeman and start to build something that's worth cheering for, as I'm sick of my father (a cule) cheering for a club that is very Messi-dependent, it is not even funny anymore.
Moreover, I'm sick of seeing RM winning CL's with ease and now leading in La Liga because their bench is phenomenal and to be brutally honest, only Isco is miles ahead of Rafinha, Gomes, Denis if they were 3 in 1 player, let alone the others like Kroos, Modric etc.
So, the only way that Barca can become a serious team again and battle in all fronts bravely, is to have a proper bench... not jokers like the one you currently have. Also, for Sampaoli to make things work at Barca, he will need Arthuro Vidal or someone like him (hard to find)... not even N'Zonzi cuts it the way Sampaoli plays.... a box to boxer with a lot of experience, a hard tackler etc. which Barca also lacks, and to be honest, the only team suiting Sampaoli perfectly would be RM at the moment.
So cut the crap and send a letter to your management or something, become a serious team and give Messi some break... he can't win all the titles himself... let him be a bit like Cristina (no duels, tap-ins, penalties etc.) and still wins Ballon D'or.... Messi deserves that or even better. Lastly, Neymar needs a slap behind the neck to.... for the countless chances and balls he is missing/losing over and over.