I think they would. My guess is that IG completely disrespected TL and dismissed prepping for semi's in exchange for having a full week to prep against SKT/G2 which would give them a huge advantage in the finals. They expected to beat TL without specific preparation to have more chance at winning the finals. Now this backfired hugely and they were unable to adapt to the style of TL's gameplay (which was executed exceptionally well).
G2, however, have a longer history of fighting TL and know exactly what the team is like. TL has a very excplicit and predictable playstyle if you've faced them enough. This was shown in the finals where EVERY move of TL got predicted and answered to before it happened. Jankos in particularly was always one step ahead, but it's most likely a team effort.
IG are still the nemesis of G2 (and EU). Until proven otherwise, I have my doubt about a G2 victory over IG.