Obviously this is not just an SaaS problem. Companies fold all the time. If you are dependent on some external capability, you'd better have a plan for business continuity. And if you have entrusted your supplier with important assets (e.g. data) you'd better be able to get your assets back quick.
A pessimist might regard this risk as a reason to avoid SaaS altogether. But I don't think Microsoft employs many pessimists. For his part Gianpaolo sees this risk as an opportunity for some enterprising SaaS undertaker - selling services to those whose beloved supplier has gone to the great SaaS graveyard.
I prefer to see this as an architectural challenge:
- How can we design a robust network of services, one not affected by a single point of failure? (This is of course a classic problem of distributed systems.)
- Are there patterns of collaborative networks that will stand up to the loss of any single organization in the network?
- What are the appropriate SLAs to support these patterns?
- And what are the interoperability requirements to make this work?