what happen if the load is a high resistance ( let's say 100K )
The more the load resistante increases, the less voltage you´ll have in the 1k resistor, due to the fact you won´t be able to source 1mA as load resistance has increased and power supply is 10V. That 1.6V will reduce as well, and the transistor will be as saturated as possible. Together with all of this, base current will increase as less voltage will be dropped across the 1.6K resistor. And finally, alongside with that, your 1mA current source won´t hold and the current will decrease.