Mining with a block reward is definitely required (either with transaction fees as block reward, perma inflation, or both). If you don't know why, read my thread:
IOTA - Permissioned ledger Russian extortion schemehttps://bitcointalk.org/index.php?topic=1414866.0If you think a blockchain can work at all without a block reward then you probably don't need one for permissioned mining. A miner can enter the system by mining for tx fees, which must be paid by existing participants in order to transact.
This does have the unfortunately (failure) equilibrium you pointed out in a slightly different context, where no one transacts but everyone just hodls at some high fantasy price and pretends they are rich.