It will dry out but will never be like the rest of the antler, never done a fallow but have done quite a few Roe and a couple of Red
where I have left the velvet intact it needs careful handling when boiling but it can be done, if you can still feel the points soft under the velvet this may be a better option, if you decide to do this try to cover the antlers with something
when boiling the head to keep the steam of the velvet, as A the steam can make the velvet slip, and B it tends to turn it ginger.
Not sure if or what you could treat the velvet with to make it last, some of the heads I have done in velvet have lasted better than others some done nearly twenty years ago are still OK.
If the points are still soft you will also need to careful of fly stikes.
Maybe someone else can help with treating the velvet, or alternative ideas on what to do with the soft tips.
Depending on how soft the tips are you may lose them if you remove the the velvet