It would appear that just like they promised a few months ago, Chelsea have been actively exploring options to increase the capacity of Stamford Bridge to something more viable in the modern economy of elite-tier football.
Previously, the emphasis had been on building a new stadium, but losing out on the Battersea Power Station site seems to have put any such designs on the back burner. While there are numerous significant and often talked-about roadblocks facing Chelsea in any potential expansion (cost, local laws, land claims, etc), one project consideration that hasn't gotten much play is what would Chelsea do while Stamford Bridge was redeveloped.
The major renovation activities of the '70s and '90s all occurred as Chelsea continued to play uninterrupted amongst the construction equipment and half-built stands. This time, it would seem that we're exploring more efficient but also more drastic temporary solutions.
In case you can't read the small letters, the plan appears to be to move to Twickenham for at least a season in a couple years. The rugby union have confirmed that they've received an inquiry from Chelsea in this matter, though no actual talks have taken place (yet). Twickenham, the second largest stadium in England and fifth largest in Europe at over 80,000 capacity hosts rugby union almost exclusively; it's unclear what the likelihood of granting Chelsea such a privilege and significant exception to that rule may be.
In any case, this certainly sounds like a positive step in potentially solving the stadium-size issue while also maintaining the club's spiritual, physical, and historical ties to the one and only home ground we've ever known.