I think if she releases a Cedric Gervais type remix for Wildest Dreams next that could do really well and then end the era with New Romantics, which she can market as a new single because 1989 Deluxe wasn't even realised in a lot of places. Its obvious if she just releases an ordinary track of 1989 it will have the same problem as Style, which was that everyone already owned it from buying the album so it didn't sell much.

August 2015 - I Wish You Would
November 2015 - Wildest Dreams
February 2016 - New Romantics/Out of the Woods
May 2016 - Clean (last single)

August 2016 - New lead single T6

Lol we'll get at best 2 more singles. There's always a 6-7 months gap between her eras.

On iTunes US right now:
#269 Wildest Dreams
#272 New Romantics
#275 Welcome To New York
#335 Wonderland
#357 You Are In Love
#541 How You Get The Girl
#685 All You Had To Do Was Stay
#698 I Know Places
#792 Out Of The Woods
#1098 Clean
#1148 I Wish You Would
#1387 This Love

Wildest Dreams and New Romantics are definitely the right choices.

5. Out of the Woods
6. Wildest Dreams
7. New Romantics

Anything BUT I Know Places

5 - Out of the Woods
6 - Wildest Dreams

5. Out of the Woods: August 2015
6. Either Wildest Dreams or a new song from a re-release: November 2015

AYHTDWS is everyone's fave, huh? I'll go with that. But, sis better release Wildest Dreams after, then New Romantics as the era closer.

5. How You Get the Girl
6. Wildest Dreams/Out of the Woods

5. Wildest Dreams
6. New Romantics

No doubt 6th single will be New Romantics as the era ender. 5th single will be a harder choice, but I think Taylor will go with either Wildest Dreams or Out of the Woods.

5. AYHTDWS

6. I know Places

7. OOTW

8. Wildest Dreams

9. New Romantics

The fifth single should be "Out of the Woods".

I think they should just stop the era with 5 singles but if they do go along with 6 singles then the sixth single should be "Welcome to New York".

Wildest Dreams
New Romantics