The new core set should be out end of the summer. I really like core sets. Mechanics tend to be the streamlined evergreen types like trample, flying, reach, +1 counters etc...as a result the cards tend to play better with a mix of more previous sets. Sometimes you get mechanics that don't transfer well outside of their specific blocks. For example, the new energy mechanic is really only in two sets Kaladesh and Aether Revolt.
I'm on the hook for some of the next set pre-releasing this weekend. Planeswalkers are expanding to uncommon cards, so more choices and easier to get. The kids love planeswalkers so we will be buying some product. Just not sure what or how much just yet.