Well, max gold should still be less than the ADC/APC/top laner.
The problem I could see with tying support gold to the ADC is that this already takes place with kills and assists. It could lead to a very fast snowball in bottom lane, as both the ADC and support start to fall behind in income. Well faster snowball. Pro is it would reward supports that keep their ADC in lane and farming. Con is sustain supports make for less excitement in the bottom lane. HMM Since I like playing sustain supports, this may not be the problem I thought it was.
So would we loose the gp10 runes or masteries? Not necessarily a problem, but things to consider.
Someone posted on the old forums about ideas for more non-support ward items. And changes to the masteries to make supports plug points in for much better wards, better range, longer duration, etc. So support vision becomes more powerful on a per unit basis, while wards are a little more accessible to all.