How hard? It’s got to be upgraded with all of the other Google products on backend changes. If Google makes a change to how they internally access search, or how they respond to incoming text messages, or anything else, all of their old products have to update with it.
As a devout Android user, can I criticise for a moment? Saying “screw Marco” is part of the reason why he has such an animosity to other platforms. He makes criticisms well known, and he isn’t afraid to speak his mind. Stop roasting him for his comments – he was, until recently, a one man team working on a one man project. From a development standpoint, it’s a nightmare to develop for multiple platforms. You aren’t doing anything but encouraging a negative attitude towards him.
In more recent times (especially on Accidental Tech Podcast instead of B & A), Marco’s said several times that Google is trying to keep control of their platform and that they’re doing an okay job. He’s not interested in developing for it, but I think part of that is just that he’d prefer to develop for the platform he uses (which is iOS). His primary reason for building Instapaper is that he wanted it, not out of demand from around the nation or anything.