Each Nano account is its own blockchain. These accounts interacting form the block lattice. So it's not as though there are competing block lattices in Nano. In

Each Nano account is its own blockchain. These accounts interacting form the block lattice. So it's not as though there are competing block lattices in Nano. In Bitcoin there can be a sidechain that can overtake the main chain (if the sidechain becomes longer than the main chain) and then cause a reorg of some blocks. But I don't think anything like this is possible in Nano. You'd have to ask the devs though to know for sure on the official Nano forum at forum.nano.org In terms of the incentives to keep the network running without mining fees or proof of stake rewards, the Nano community and devs think that merchants and other services using Nano will save significant amounts of money by not having to pay credit card processing fees. This will incentivize those merchants and service providers to run their own node (which only costs around $60 per month) in order to keep the network healthy and decentralized. The lack of mining fees and proof of stake actually disincentivizes the kind of centralization we are seeing with Bitcoin mining.