Using the new Oystercard for 2-for-1 deals?

No, according to the Days Out 2 for 1 FAQ, which I am betting will not change in January. http://www.daysoutguide.co.uk/faq.aspx . Travelcards bought at rail stations should still meet the requirements. You may find this link helpful. http://tinyurl.com/ydq2jod

It wont' work even though the Oystercard can now be used for all National Rail trips? I thought that since this will go into effect, the Travelcard will be used less...

The 2-for-1 offer was never really intended to be used with local London travel passes. The main purpose of the offer was the rail companies trying to get people to use off-peak trains into London from the rest of the UK. The fact that train companies also sell London travel cards was just a handy bonus, no one can be certain what will happen but I would be very surprised if they extend the offer to Oyster when (if?) travel cards are phased out.

P.S. I'm sure you know but to be clear to other readers, you can not use Oyster of all National Rail trains, just journeys with in Greater London (zones 1-9).

I see. Would I be able to buy a national rail ticket from Zone 3 (Hither Green station) into London then? Should I consider doing this on days where I'll find the 2-for-1 deals especially useful?

That should work, although I won't pretend to be a London travel expert - I've only ever been as a tourist myself.

As to should you consider it? It depends on how you want to use it; single entrance to the tower, for instance, is £17 so that would probably make sense even if you "lost" money on the transport costs.

All these are hypothetical though as you can still just buy a travel card from National Rail and use that to get around London and get the 2-for-1s. AFAIK there are no plans to stop selling them in the short term.

Sherry,

Yes, you could buy one-day, zone 1-3 National Rail travelcards for each day you plan to take advantage of 2-for-1 offers and use Oyster cards as PAYG for all other days.