Yes, it is expensive but possible to discover any funds associated with a seed, provided there are set limits to:

1. gap of address use (e.g. 20)
2. depth of hierarchy (e.g. 6)
3. gap in use of parallel branches (e.g. 0) 

I would pick the limits in brackets above. 

Regards,

Tamas Blummer
http://bitsofproof.com

On 26.04.2014, at 12:48, Tier Nolan <tier.nolan@gmail.com> wrote:

> Maybe the solution is to have a defined way to import an unknown wallet?
> 
> This means that the gap space and a search ordering needs to be defined.
> 
> Given a blockchain and a root seed, it should be possible to find all the addresses for that root seed.
> 
> The hierarchy that the wallet actually uses could be anything.