Nearly 100% CPU usage isn't necessarily bad, you can still have games run well, but it just means that with every program you have open (chrome, discord, whatever) you sacrifice a little bit of FPS. Blackout will probably be better optimized in a few months after they patch if a few times, it seems like the COD titles might take the PC market a bit more seriously moving forward, which may mean that your 4690 will handle it with ease. The R5 2600(X) will certainly handle it. Core for core, the 2600 is actually similar in speed to the 4690, but the extra 2 cores and hypertheads will help with background tasks and possibly the game itself. It also supports overclocking and if you throw in some decently fast RAM you may be able to get 10-15% or so extra performance over stock. Honestly if the performance is actually bothering you a bit, you may as well just upgrade now and sell your cpu/mobo/RAM. Now is a good time to upgrade. In addition, Zen 2 is around the corner (probably early 2019) and your motherboard will support it, so there's also an upgrade path for the future. If you're ok with the performance in games on your 4690, then there's no reason to upgrade.
But to directly answer your question: Yes the R5 2600(X) will easily handle those games, but the 4690 will probably handle them pretty well too. Maybe just play for a little bit and decide if the performance of your CPU is something you're satisfied with, if it's not then consider upgrading. If you do end up holding off, whatever intel ends up replacing the i5 8400 with will also be a great option for you.