Luffy will have 4 conflicts with Shanks:
4. Shanks being a Celestial Dragon. Luffy won't hate Shanks for being born as a CD, but Luffy finding out Shanks has visited Marijoa/lived there, and had hidden his lineage, will make Luffy think twice.
3. Kidd getting ruined by Shanks. Luffy will be fine with Kidd losing, but, Shanks destroying the Victoria Punk may be too much for Luffy, who clearly views Kidd as a friend, by now.
2. Bartolomeo. This is a huge one: Bartolomeo is Luffy's subordinate, and a man who's helped save Luffy's crew. This will lead to a big fight. But, the worst, by far, is:
1. Shanks stopped Kaido from aiding Whitebeard in Marineford. Shanks knew Kaido + Newgate would defeat the Marines, and destroy global balance/peace. So, Shanks chose to protect global peace, over aiding his Captain's Son.
Luffy realizing Kaido wanted to save Ace and that Shanks stopped him is going to create a huge hole in their relationship. Interested to see how Yamato handles learning her dad she hated for totally legitimate reasons wanted to save Ace, too.