For every cent miners earn mining Bitcoin on a SideChain they insulate themselves from the disruption in the inevitable 50% revenue drop, and for cent of insulation we move closer to Kevin Dowd's inevitable prediction.
Miners don't need to mine sidechains in order to gain more revenue - it's just as viable to mine more transactions on the main chain.
If there's a demand for 1000 tps, the main chain should be allowed to satisfy that demand.
This gives the miners the revenue they need to wean themselves away from dependence on the block subsidy.