If we are playing Argentina at the Cake Tin I would expect Messi to stay back for the home leg only, if at all. There is very little room for romantic notions in the brutal business that is professional football.
They (put Chile in the same frame of planning) would send a Team B here and get a minor win, even 2-1 will do, or even a draw. I do not think they would see any value in subjecting quality players to rigours of long-distance travel. They would want to ensure the result is beyond any doubt in their home leg. In other words, they would do what we did with the Solomons.
would agree with that if the 1st leg was in South America, but it's here so whoever it will be will be wanting to put the game to bed early and would send their strongest XI - given that only 3 of Argentina's team are actually based in Argentina, the rest in Europe (except 1 in Mexico which is still an 8-9 hour flight away), and only 9 of Chile's current is based in Chile, the players aren't going to have a big problem with long distance travel (and they'll go 1st class)
I hear what you are saying, but in your scenario their Team B would simply need to travel here early and acclimatise ahead of their away leg, that they do not have to win by much. It is their players that do not have to travel at all that would win the their home leg for them.
Sorry to sound defeatist, but my point is about the difference in team depth, and not just individual quality. Any of the CONMEBOL countries, even Venezuela, could easily field two separate teams for two different legs; and those placed mid-table (5th out of ten teams) is simply very good indeed. In contrast, we simply do not have players of good quality to rotate for the intercontinental travel if the 2nd leg is in South America, as you say.