An alternative would be targeting a single set of hardware that's likely to be around a really long time. I'd be ok with that and something like a Raspberry Pi, but only if all the hardware was open. Of course, then you're in more of a 68k Mac space where hardware choices are extremely limited.
I think we are talking about a different niche.
If so, no need to think in terms of catch-up. Rather: work out the design values of this niche.
Lots of ideas, but this thread is already deep. I have created #dinghy on irc.freenode.org, would be interested to discuss further.