Is there any chance to support Lamport signature in the future? Comparing with traditional private key cryptography, Lamport signature is much more easy to implement. It is also QC hard. There are 2 major problems for Lamport signature: one-time-use only and large size.

The one-time-use only problem can be improved by using a merklelized public key (http://en.wikipedia.org/wiki/Lamport_signature#Public_key_for_multiple_messages).

For sig size, it's actually not that big. Using Hash160, the public key will consume 800bytes, and the signature will consume 400bytes, so the total will be 1.2kB (a few more bytes if merklelized public key is used). A transaction like this: http://blockchain.info/tx/8e17ed76cf51a9adcbb284365c2aff6bf28f7fa8259286dd1a93ec1cd47a81ca already takes 1.5kB. However, using the CHECKSIG 2.0 I proposed at https://bitcointalk.org/index.php?topic=258931.0, it is possible to sign multiple inputs with only one signature. Therefore, using Lamport signature would not be a big problem.