It is possible, although it would be more development for Steemit, more things to test, which would mean more time before the fork. There is already a lot of pushback from the hardfork containing too many changes. At this point, most of us want to get something out the door so we can start working within an improved system. There will always be the option of making more tweaks later (such as updates to witness pay), and after the hardfork - we will have a SPS to pay for such things.