Probably not. The Carte Senior costs 57€ per year and should give you at least a 25% reduction.

I dont think you can get the discount, unless you purchase your tickets in France.

Here is some information that I found:

Travelers age 60 and over can buy
the Carte Senior, which grants 25% to 50% reductions on first- or second-class domestic rail travel, depending on the day and time of travel and on how early reservations are made. 25% reductions are also available on train travel to 25 European countries on the RailPlus network. Cards are for sale in France only at railroad stations and at French travel agencies for 56€ and are good for one year. Even without the Carte Senior, travelers age 60 and over are eligible for the Découverte Senior discount—a 25% reduced fare on many TGV trains. Proof of age is required.

Are the "senior" discounts allowed for folks who are not French residents/citizens?

There is a senior discount fare called "découverte senior" that gives seniors 60+ a 25% reduction in the "blue period" (which I take to mean "off peak" times) on Ter and Intercity trains. You must present proof of age to the conductor on the train.

Here are the exact words from a Q&A on the SNCF site:
http://questions.sncf.com/questions/30163-decouverte-senior-prix-sans-carte-senior

" pour vos voyages ter et intercités, grâce au tarif découverte senior (+ 60 ans), bénéficiez de 25% de réduction en place assise sur vos trajets commencés en période bleue

a bord, présentez votre billet au contrôleur avec une pièce d'identité pour justifier votre âge."

As far as I know, this discount is available to anyone meeting the criteria. I'm not French and I've used it twice with no questions asked. When purchasing tickets, it will be applied automatically when you give your age as 60+ and you are traveling on a Ter or Intercity train during a blue period.

Note that it is not available for TGV or iDTGV trains.

The first senior discount I ever received was on a TGV ticket. I clicked 60+ as you did and bought the ticket. A ticket agent or train attendant might check your age but you will have your passport to prove it.

Thank you, that is very helpful info. I had noticed the "60+" tab but assumed it was available only with one of the French "senior"cards. I checked one of our future TER routes, and the discount automatically appeared for routing during "periode bleu."