No, miners will earn similar to what they are doing right now because they will be getting massive profits from transaction fees itself. So, there will be no need for them to be leaving off their operation of bitcoin mining; they will happily continue forever their mining process and this is how bitcoin network and mining system was designed.
There will be no changes are needed hence we cannot expect developing team will be bringing up something new. Because, the basic economics of bitcoin is decided and if any changes into that, will make investors and miners disappointed.
Bitcoin will be worth a lot more in the future, so miners will live comfortably off network fees. The block reward is just an additional incentive to help attract as much miners into Bitcoin as possible. After the network is solidified, fees will be their only source of income. Neither you and I will be alive when all of the Bitcoins are mined, so we'll never know what will happen by then. Either Bitcoin keeps going up in price or goes all the way down the drain. With how Bitcoin's been progressing since day one, I'm certain its price will increase to "infinity and beyond". Just my thoughts
