[MENTION=148475]MRM69[/MENTION], Toyota only did this with the 4runner Pro colors ending up on Tacomas the following year. Example: 2017 Cement, it was only on 4runner pro and Tacoma Pro in 2017 but on other none Pro Tacomas in 2018 (i think Tundras too) but NOT on other trim levels of the 4runner in 2018. Same with Inferno and Quicksand, also looks like you can not buy a cavarly in 2019 on a 4runner.
So.... unlikely they will offer any of those again on any trim in 2020, the last year of the 5th gen, which will be annonunced early 2019, on dealer lots in September 2019 as a 2020 model. Most likely a 6th gen will be announced early 2020 and at dealers fall of 2020 as a 2021 model.
Now, will they make more cool funky gray, red and blue colors? Of course, but they will be different.