"Once our valuation rises and the cost becomes prohibitive, we’ll move to an extended exercise period model instead, where you will have 10 years to purchase your options. By that time we’ll either have had an exit (in which case you can do a cashless exercise), or we will have arranged some other form of liquidity."
The 10 year exercise window likely makes this unnecessary, but if not he says they will arrange for some form of liquidity.