Being the Devil's Advocate for a moment, one could reply that once "strong AI/sentient/sapient artificial life is actually close to becoming a reality" then it may be too late to start the discussion as there will a lot of vested interest and, given the kind of money this will cost and the groups investigating it, those interests will likely be rather powerful and influential with ludicrously well-funded lobbying arms.
These groups will hold up the discussion while progress continues unabated by the kind of caution that is being advocated, much as, for example, leaded petrol continued to be produced and used, with the powerful GM, Standard Oil and Dupont spending vast sums and influence to buy everyone from politicians to university deans who might help them discredit research into negative effects of lead.
My point is not that anything bad will happen if we continue our research into advancing 'machine learning' towards real artificial intelligence (whatever that means) and on towards sentience (again, whatever that means). My point, in my self-appointed role as Devil's Advocate, is that discussing the potential issues now is not necessarily too early.
That discussion, if it is to be had, must be reasonable and proportionate and there are clearly those who are far from either. That doesn't mean, however, that the discussion is not worthwhile, just that the public face of it has veered into sweeping statements of a generally extreme and often alarmist nature. Which is the way that media reporting of technology tends to go*, but that says more about them than the importance of the discussion itself. There are always people at the ready to claim - or extend - their 15 seconds and willing to say whatever makes for 'good' television/headlines in order to do so.
I think the starting point to any reasonable discussion must be an agreed-upon definition of the terms - especially 'intelligence'. Without that, it's impossible to debate the threat that it may or may not pose. Some definition of 'AI' are almost self-evidently dangerous but others - such as those used by marketing departments - are benign to the point of banality.
For me, intelligence is the ability to reason both from specifics to generalities and vice-versa and not just within one field but across all fields - to be able to see some examples and, from those, identify the important commonalities and create some general principles. Then, from those general principles, not only figure out further, unknown instances but even to imagine non-existent possibilities and applications; we can imagine things that might exist or don't exit or even could not exist.
But, again, all that discussion is not invalidated simply because some people wish to get their names in the media.
* - That the LHC has - so far - stubbornly failed to destroy the universe despite the squaw(r)ks of the kind of people our collective media rejoice in interviewing is much to my disappointment.