There's basically no point scientifically for doing the four-planet flyby again. Since Voyager, we've already done much better at Jupiter and Saturn with years

There's basically no point scientifically for doing the four-planet flyby again. Since Voyager, we've already done much better at Jupiter and Saturn with years-long orbiter missions. A quick flyby wouldn't get us anything we don't already know at those. Voyager gets the mindshare because it was first and the four-way slingshot is fun to visualize, but the reality is that Galileo and Cassini and Juno delivered thousands of times more data. We could use more investigation at Uranus and Neptune, but we'd get much more out of extended orbiter missions to those rather than another quick flyby. A Uranus orbiter is currently one of the higher priority missions in planning, and there's a launch window for a Jupiter-Uranus slingshot in 2034 or 2035. (What I wonder is, how much planning do these things need? Why can't we just launch another copy of Cassini to Uranus and skip all the expensive design? You'd need some changes to antennas and power supply for a more distant planet, but the scientific instruments and computing platform should just be reusable designs.)