The free new coin can be dumped, but there are risks involved. You have to ensure that you safely 'harvest' the new coin and don't lose out because of replay attack. Some people are lucky enough to dump the new coins quickly and profit.
Yes but dont expect to see this happening again. Cuz what is known about bitcoin gold almost nothing, ok if you get free coins but this time wont be that much maybe this bitcoin gold will be worth something 100 dollars maybe but this is free at the end. No wallet not a single exchange have made some announcement that they will hold them, so this will be nothing at the end.