I think you don't really grasp what 2^160 actually means... let alone 2^2048...
This +1.
To the supports .... D&T rant mode engaged.
1) Bit strength alone is utterly meaningless. ECC was designed to use a smaller key size yet produce the equivelent security of larger key sizes used by RSA. 256 bit ECC has the equivelent security of 3072 bit RSA. The whole POINT of ECC was to reduce key sizes without reducing security. Increasing the size of the hash to larger than the ECC key is a good way to just waste space. It does absolutely nothing.
2) There aren't even any vetted ECC curves beyond 512 bit because it makes about as much sense as idiot LEET hackers speculating that if 2048 bit RSA is good then 4892374190289378952347589347528945 bit RSA must be even better.
3)
160 bits can't be brute forced. Period. To put it into perspective the entire bitcoin network has performed roughly 2^56 hashes and comparisons. If the Bitcoin network was one trillion times faster (note that is roughly a million times more computing power than the entire planet combined) it would take "only" 80 quadrillion years to have a 50% chance of brute forcing a single 160 bit hash. Most miners understand difficulty so brute forcing a 160 bit key is like a solving a block with a difficulty of 79,228,162,514,264,300,000,000,000,000
4) Larger key strengths are useful in the event an algorithm is partially compromised HOWEVER it is more important to use well known and vetted algorithms which are less likely to be compromised in the first place. Moving to Bobs Leet 2048 bit hash is of little utility if it is broken wide open providing about 20 bits of effective security vs no practical attacks on RIPEMD-160 or SHA-256.
5) Public addresses are the product of a double SHA-256 hash AND RIPEMD-160 hash of the public key. This provides resistance to cryptographic attacks as it would require not just a flaw in one algorithm but a significant exploitable flaw in two completely unrelated and highly vetted hashing algorithms to have any useful applications.
6) Nothing is free. Larger keys, larger public addresses (hashes), and more decimal precision takes up space. The idiotic idea of going to a 2048 hash would increase the size of all transactions by a factor of nearly 13. To put it into perspective if the network currently used that the blockchain would be nearly 40GB and growing by 5GB or so a month. All those scalability limits (bandwidth for a node, computing power to verify tx, annual storage growth requirements, time to bootstrap a new node) would all be increased by a factor of 13.
Your arguments are valid.
Actually I already realized validness of these arguments before, however I am a hardcore crypto freak and i like if my cryptography is blazingly, incredibly strong. I actually use 4096-bit VPN keys to communicate between some of my servers even though i know very well that 2048 is more than enough.
So, now that we have determined that more cryptography is not necessary, what do you think about adding
more decimal places ?
This is not an unrealistic future problem. If in 30-40 years Bitcoin becomes world's #1 currency, then 8 decimal places will not be enough. Why not simply add them now while it is extremely easy instead waiting for problems in the future ?
When Bitcoin becomes widespread, it will be much more difficult to change anything than it was to change from Ipv4 to Ipv6 protocol (because of all the mining hardware).
Bitcoin may never scale to a level where such precision is useful. Say we increase it to 16 digits. Why not 48? or 96? or 2000? Now you likely are thinking 2000 digits, now that is stupid. 9+ is really no different.
However, that argument is invalid.
Bitcoin "may never scale" they said. But it also MAY scale - what's then ?
This is a foolish "let's wait for the problem appear, before dealing with it" kind of thinking.
Say we increase it to 16 digits. Why not 48? or 96? or 2000? Now you likely are thinking 2000 digits, now that is stupid. 9+ is really no different.
Really ? That's a simple problem.
We can calculate the minimum unit from following algorithm:
# [Total value] = all Dollars in circulation + Euros in circulation + Yens in circulation + CNY in circulation + all the other currencies
# Convert [Total value] to amount of smallest units/fractions of the earth's cheapest currency (*excluding* internet currencies and currencies of countries with hyperinflation)
# Add one or 2 zeros.
There you have it. The humanity will probably never require more units of Bitcoin than that, even if Bitcoin becomes #1 World currency and everybody on the world starts using Bitcoin instead of other currencies.
Currently, total amount of the smallest units of Bitcoin is 2,100,000,000,000,000 which is just over 2 thousands of trillions (USA scale). Is it enough according to the equation above ? I highly doubt so.