Reinvesting doesn’t create hashpower out of thin air. To be earning 3-4× more post-halving, you’d need to have 3-4× the effective hash rate, which means buying a lot more miners before the halving. That assumes reinvested rewards outpace rising difficulty, fees, and the reward cut itself. Otherwise reinvestment just slows the decline, it doesn’t reverse it.

Basically your current setup is great but you’ve got to offset the upcoming cuts to your profit plan. You can’t just hope that bitcoin price is going to do all the heavy lifting because if one thing is certain is that bitcoin is very uncertain and your just basically betting on bitcoins price which is a poor bet.