Actually for vineggard (and also pogacar) it's the perfect year to try tour and la vuelta double. There is an extra week between tour and vuelta, usually it's 4 weeks but this year 5, so it gives an extra week to do a training camp after some post-tdf rest.
And also for vinegaard , roglic will take the pressure off. He had his most dominant season, winning itzulia, dauphine and tour, he doesn't have to prove anything, he can try what it's like to go for 2 grand tours on a season without the pressure of the expectations of teams and fans on his shoulder. The team should focus on roglic.
It took froome several seasons to perfect the tour-vuelta preparation and do the double.