I believe there is a subtle change going on at the USPS: the move away from coil issues.
During the 1920s and 1930s, the USPOD issued coil stamps for a variety of denominations Ė not just the first class letter rate. Coils of 4Ę, 5Ę, and even 10Ę denominations were available in addition to 3Ę coils for letters. Recently, coils have shifted to just special undenominated service rate stamps (bulk rate, non-profit, pre-sorted, etc.)
Ignore the current Flags of Our Nation issue (which is a special commemorative issue in coil format). What choice is there for coils? To the general public, not much.
The USPS continues to release undenominated special rate stamps for large mailers who buy coils by the thousands for their huge mailings. They like coil stamps because the use of a stamp on the envelope implies that it is not junk mail. And with stamp affixing machines, itís a highly automated process to attach these coils to envelopes. They get a lot of benefit (appearance) from the use of coils and at a reduced cost (through automation). I donít see these coil issues going away.
Why havenít the Forever stamps been issued in coil format? Is it to discourage their use by small to medium size businesses? The USPS sells Forever stamps up until the day of the rate change at the lower, old rate. Businesses that donít qualify for reduced postage rates could buy huge quantities of the Forever stamp and (if they were coiled) automatically affix them. The savings could be quite large. But because the Forever stamps are only issued in booklet form, they would have a large expense to have an employee manually apply those stamps to letters. Itís not profitable for a business to use booklet stamps.
Some in the general public would buy a roll of coil stamps from the USPS and keep them in a desk drawer for use. But with the Forever stamps, they buy them instead so that they donít have to fool with unused remainders of stamps at the old postage rate.
I think the non-denominated special rate coil stamps will be around for a long time. But other coil stamps are going the way of the dinosaurs.