Open your fucking eyes. we all go to bottleneck apocalypse. Didn't you mind that vanilla client already makes your computer unusable during sync process? Imagine now that Bitcoin has 10k transactions per block instead of 200. Your PCs will just die.
You have no idea what you are talking about. 10k transactions per block is peanuts for even a low end CPU to handle. That is less workload than computing a single frame of any modern PC Video Game. The biggest bottleneck now is the disk read to lookup transactions which is resolved in v0.8 by only storing the unspent output transactions in RAM which is ALL YOU NEED to verify incoming blocks/new transactions. The unspent output set would have to grow by atleast a factor of 30x before storing it in RAM(4GB) becomes an issue. Even if it does, you have on average, 10 mins to process it, something your mobile phone CPU could easily do.
Lets bring it up to 10k/s and assume that the max block size was increased to handle such loads and network bandwidth is not an issue. We could store the unspent output data set in your consumer grade GPU and process them all in realtime.
In short, processing power/harddisk are cheap and plentiful even on low end PCs TODAY.
Memory/Network bandwidth is relatively expensive especially in some parts of the world.
The whole point of having every node process everything is Bitcoin's core philosophy of being trustless.
You dont have to rely on anyone else to verify the validity of any transaction.