Yes, it will cost you money every year. I’m giving it a year to prove that it’s worth the money. (I gave Day One, Ulysses, and Bear each a year and ended up turning them off when it was clear that as excellent as they were, they didn’t do enough for me to justify the outlay.)
I’m less about simplifying my apps than simplifying my workflow. For instance, as I’ve noted ad nauseam, I use Devonthink, Obisidan, Notebooks, and Finder to manage the same set of Dropbox folders. Each of those apps has its place in my workflow, and it would be a bumpier ride if I tried to use just one of them to do everything.
There’s one way I hope Readwise Reader will both reduce the number of apps I use and simplify my workflow: reading and highlighting epubs and pdfs on both my Mac and my iPad and getting those notes and highlights into my collection of markdown notes. I’d basically given up on being able to do that simply and straightforwardly.
I don’t know if I will use Reader as an rss reader and read-it-later service. At the moment I use News Explorer and GoodLinks for that respectively and I’m not sure I want to switch. What I may do is use Reader for articles and feeds that are directly related to the areas in my personal syllabus and its areas of focus and use the other two apps for casual reading.
ETA: @Pupsino is 100% on the money re newsletters. I’m in the process of moving as many as I can out of my email inbox and into Reader.