Kind of depends what you're after. ARM chips are very good in relatively low power, low usage situations like mobile devices but they're simply not in the same league as Intel or AMD for 'desktop' stuff. The best ARM chip is, what, Dual core and 1GHz? You can buy an iMac today in which the main chip is 3.4GHz and quad core. There's simply no comparison. There are plenty of desktop applications ARM equipped devices can do equally well, but there are an equal number where frankly they simply wouldn't be up to the task. And some of those are things people are going to want to do more of in the future, like HD video processing.
If you wanted to build a desktop machine using ARM it would have to be more like a games console than a current desktop PC. The ARM 'cpu' would in fact not do all that much but would be surrounded by a lot of custom high speed silicon that was good at specific tasks or set of tasks and all the CPU would do is shuffle tasks around between them.
Also ARM have stated they have no intention of going to 64-bit addressing any time soon, which will put their chips at a disadvantage when dealing with large datasets like high megapixel images for example.
ARM chips are very good but they're tailored towards what they believe their market is - low power consumption 'consumer' devices. I'm not sure that fits with where the desktop PC is, or where it's going. Even if the future of HCI is with tablets and 'sub tablet' devices, you're still going to want a big lump of horsepower some of the time. IMO you can't
just have an iPad, unless your needs are very modest. Now some people's needs are modest but I actually think the percentage of people like that is falling, not growing. As we all become used to playing with HD video and multi-megapixel cameras and pulling huge amounts of data around over wireless networks, we're actually going to need more computing horsepower, not less. There's no reason for that horsepower to be in what looks like a desktop PC today and for us to 'drive' it the same way but it does have to be somewhere.
if they maintain the APIs across the transition, most developers won't care all that much, it'd just be a recompile and a bit more QA. And Apple are already some way down the path towards the 'distributed processing model' with things like OpenCL and Grand Central Dispatch. I'm just not sure Apple are there yet and I'm fairly certain ARM chips of themselves won't get us there - first they'd have to decide to go that path, then there'd have to be an awful lot of backroom development afterwards. That may be going on but I don't think it's going to happen in the next few years or anything.
Jon
