I'm pretty sure the weekend chase missions will stay exactly like are now. It's just that we will get two more events during weekend only. The reward shown there are the potential best rewards. Just right now you coul get tendo or naruto ninetails chakra there with a big quantity of luck.

Maybe you don't know that if the ninetails doesn't die within 10 minutes since the starting time his hp gets reduced the next time you fight it so, on friday, if you had a 28millions hp wb on Thursday you'll see a 17 millions one that means not only less coins and exp on Thursday but also on friday.