Controlling multiple triacs with microcontroller for light dimming: where to use optoisolators
The basic triac driver circuit sinks current into the gate (trigger) input, to ground. If you can connect the grounds of all involved triacs together, you an use one microcontroller to drive all triacs (via a suitable drivers, of course). I hope you realise that this makes your microcontroller circuit 'life' (= connected to the mains), so unless you have an isolated programmer it will make your debugging process tedious.

I have my doubts that this approach will save you much, because optoisolated triac drivers are small and cheap. The snubber R + C are likely to be your largest components (unless you need to cool the triac). Maybe you can combine the snubbers into one filter for all channels.