Is reducing support time the first step of going to have a rolling distribution?
No. Well maybe. Who knows... but the current vote was 3-0 against a rolling release.
Or there is any other purpose?
In order to go even faster as the leading free software platform, meet
the needs of both our external users and internal communities (Unity,
Canonical, Kubuntu, Xubuntu and many many others) and prepare for a
wider role in personal computing, Ubuntu is considering:
2. Reducing the amount of release management, and duration of support,
for interim releases.
Very few end users depend on 18 months support for interim releases. The
proposal is to reduce the support for interim releases to 7 months,
thereby providing constant support for those who stay on the latest
interim release, or any supported LTS releases. Our working assumption
is that the latest interim release is used by folks who will be
involved, even if tangentially, in the making of Ubuntu, and LTS
releases will be used by those who purely consume it.