Indeed, they may decide later on that having their own private chain like on Lisk would be a huge benefit. The difference is that ETH is a Bloat-chain, all one big chain; while Lisk's chain is totally independant of sidechains. A huge advantage in speed and customization.
Ofc, then it would be required that some sort of mining or forging takes place to secure the network.
Lisk forging takes place totally independant of sidechains, and those chains may be whatever algo they choose.

I'm a huge DPoS/DPoM supporter because of the amount of power it takes to secure and sustain the networks. Bitcoin and Ethereum are huge wasters of energy and resources. Delegation changes all that.
Very eco-friendly. The entire network can easily be run on minimal node cpu usage, and does away with Difficulty increases, and the constant need to buy better, faster equipment. Proceeds can then be used for far better things, like development of the code.