Yes the green bag service is being scrapped, from the Lewisham site
"The last day that you’ll be able to buy garden waste bags will be Friday 29 April and the last collection date will be Friday 15 July 2016. From June 2016 we will be offering garden waste wheelie bin collections."

The Brown Bin can take more types of waste, "grass, leaves, twigs
hedge trimmings, weeds (except Japanese knotweed*), flowers
plants, fallen fruit, house flowers, branches no more than 10cm thick and 50cm long, cut-up Christmas trees

BUT "Only put loose garden waste in your bin. Don’t use plastic bags." Which is not overly helpful if your waste is in the back garden and the bins are collected from the front. Either you wheel the bin back and forth through your house or you collect wase in a bag, empty into the brown bin and then put the empty plastic bag in, ummm, household waste bin?