I actually have greater concern for the batting than the bowling, at least in the medium to long term. Bowling wise we've got Smith, Fisher, Sears, Sheat, Shipley, O'Rourke, Foulkes etc. Not to mention KJ. Tickner is universally regarded as a mystifying selection, and he still far from embarrassed himself in this game. Sure there'll be injuries to some of those guys, but I see enough talent there to be reasonably optimistic.
By comparison, on the batting front I'm not sure there's anyone who can be relied on to replace the runs that will be departing when Kane and Conway retire in 3 or 4 years time (and Mitchell, Blundell and Latham will all be hanging up their caps around the same time). That Rachin and Phillips, a couple of guys who average 35 and 40 respectively are supposed to be the backbone of NZ's future test line-up is far more concerning than the bowling stocks.