I see a future of bloat:
* Cloud systems and virtualization on very powerful servers can be exploited to shorten the time to market, at the cost of bloat.
* Windows 7 may finally make Windows XP users upgrade, many to 64-bit machines, enabling a significant growth in amount of RAM in an average PC. This will make it more acceptable that software uses more RAM.
During the last 28 years, my experience has been, that user interfaces have had similar response time all the way. Sometimes a bit slower, sometimes a bit faster. I guess the amount of bloat always adapts itself, to a compromise between user requirements and development costs. There are currently plenty of mechanisms that favor increased bloat:
* Many multicore/multitasking techniques involve more layers, more complexity, more redundant/copied/cached data, more bloat.
* The world of programming gets more complex, and young programmers increasingly use very complex building blocks without fully realizing how they work.
* One of the most common ways to exploit multi-core CPUs, is to do work in a background thread.
Basically, there will be more bloat, because it pays. However, it also means that the amount of optimization, that can be done to code, will increase. One of the few mechanisms to reduce bloat is battery power, because increased battery lifetime is a sales parameter that justifies increased development costs. The problem here is, how do you create a mobile platform, where the 3rd party applications use less battery? Applications like JoikuSpot can quickly drain a good battery. It seems that Apple has done a good job with the iPhone, where you can use a large number of applications easily without losing all your battery power. However, Apple's methods also have drawbacks, as described in this post.
I wouldn't wonder if we will see power consumption measurement for applications built into mobile platforms in the future. Imagine a message like "This application has used 10% of your battery power during the last 15 minutes. If it continues to run, your phone will be out of power in about 60 minutes. Do you want to terminate this application?"