Today version 9.5 of Symbian OS was announced. Among other things, it features some serious performance improvements (demand paging, file caching, RAM defragmentation). Especially demand paging sounds sweet, as it'll speed up application startup a lot. This is sorely needed in Symbian, because it often feels pretty sluggish. Sure, that's the price you have to pay to run such an advanced system on limited hardware, but I know I'm not the only one who feels that the hardware can't be blamed for all the perceived slowness of the devices.
However, a faster OS might serve as an excuse for the phone manufactures to cut down on the hardware, effectively giving the same performance as current models. Another alternative is that they'll add more features and bloat, which still seems to be the main priority of the phone manufacturers (at least when it comes to smartphones), although the iPhone has at least shifted that focus a bit towards user interfaces.