I don't have access to the album to check the credits. I think Richie co-wrote about half the album and Jon had other co-writers and maybe wrote a couple by himself. Personally, I like WAN about a thousand times better than The Circle. I know a lot of people don't like it though. There are some songs on it that make me roll my eyes (the title track, Thick as Thieves) but, overall, I like it.
I honestly expect something very different from WAN if we get a Bon Jovi album without Richie or a Jon solo album though. I have nothing to base that on other than a gut feeling.
I expect that if Jon does another album without Richie he will be going for something that suits him artistically like Destination Anywhere did and something to prove he's a kick-ass songwriter that doesn't need Richie. I think that they had fallen into complacency over the last few years, knowing that whatever they released would do well enough to give them an excuse to tour. Now, without Richie, Jon will want to produce the best QUALITY album he can to prove himself again. Jon's takes pride in his songwriting and he's ALWAYS said that was the thing that he enjoyed most about the creative process. I know he's got some great songs left in him. It's time he brought them to life.
Like you said, he's got to stop trying to inspire the masses with another It's My Life. He needs to write what's in his heart.