They are shutting down some of their hardware, the unprofitable one. If they were to replace it soon (eg: in a week) then why doing the announcement and shutting down GHS on their client's face entirely?
What can this mean for the Bitcoin network?

?
Slightly slower confirmation time for the next 2 weeks, starting when they shut down this hardware (at next difficulty adjustment, just now apparently). But nothing more, there are other players, and the incentive-based mining network is a self-regulating system. It will manage.
will they sort of dump bitcoin difficulty and then when difficulty drop they pump it up again (teh difficulty not teh price) ? it makes sense isnt ?