Direct debit is rather familiar to elderly people today. As their grandchildren will see to it that they get into e-mails, photoswapping, facebooks, instant messaging etc I think that the step to using e-banking will be short for the remaining part of 65+ - especially when banks integrate direct debit into e-invoicing (standing order) and organise alert to mobile phones for arrived e-invoices.

 I don't think that lack of usability is the problem anymore. Mobile devices or e-banking systems are quite user friendly nowadays. In this case it's all about change... or changing habits

There is quite user friendly UIs in desktop environment. I would say that in mobile devices there is lots of existing technologies which can help elderly people, but not reliable solutions for the masses – yet. University of Joensuu have a research laboratory for educational technology and human computer interface focused on elderly people: http://cs.joensuu.fi/senioriklubi/english/

I think that ease of use is not the biggest obstacle in diffusion of technologies when this group is concerned. I have seen my parents, far from being elderly but still traditionally adverse to new technologies, grow into curious tech consumers. We need to segment society less by age and more by psychographics. Sure there is a correlation in certain but I believe these will fade.

How to learn an old dog new tricks is making the threshold of adoption seem lower. That can be done in part by ease of use and usefulness, the full realization of these only comes when there is sustained use of the tool in question. The selling process of the technology which predates this, is in my view more important.  The actual product with its attributes is of course at the center of the sale.