Radiant will obviously be released eventually, and it is probably a 3 or 4 year (or more) game based on the pace of development so far. Both devs have history releasing games, so I am confident they will keep working on it until it is completed. And the game is for the most part, except for some unneeded drama in the last update in my opinion, very high quality.
I think the issue that some have, is that as long as RK gets $10K a month, there isn't a lot of motivation for them to finish up the game quickly, because that is less money for them in the long run. Imagine you are getting $10K a month, there isn't a lot of motivation to push out updates quickly every month and wrap up your game in a year, when you can extend it out 3 or 4 years at the same effort. The Patron model encourages slow development, as long as it isn't so slow that supporters drop off. As we have seen with this and several other games, the best strategy is to release a great first update, with lots of lots of content, beautiful models, and an intriguing story, and then only release every 9 to 12 months. Then you can keep the Patreon cash flowing, for only a small number of hours a week of development work.
Now there are some devs who have their own internal work ethic, that keeps them working on the game most days of the week, and they have sizeable regular 1-3 month updates. Some developers even feel that as long as they are collecting Patreon cash monthly, that they owe some content to their fans every month or at most every 2 months if something unusual happens to slow down development, but honestly, this type of developer is becoming more and more rare.
But, every one of Radiant's supporters knows this, and is happy to support the development anyway, so none of us here, who are getting the game for free, should complain or discourage others from supporting the devs while they make their other games. There is no rule on Patron that devs can only have one game, and I suspect that many accomplished devs have multiple games under different names. R&K is just being honest by admitting it from the start.
I think a lot of us expected after Radiant's first release, that there would be some content every 2 or 3 months, but that didn't come from either of the devs. This was our own mistaken assumption based on the release cycles of the devs' other games. Radiant is on a 8 to 10 month cycle, and we should all just accept it. If Patreon supporters are fine paying tens of thousands of dollars, collectively, each month for the game's development no matter how little happens each month, who are we to complain about it? We can each either support them or not.