I like your point of need for preservation, react to stimuli and others as necessary but I'll posit that we can already do that with computers. Need for preservation is an interesting phrase, because I can create an evolutionary algorithm that rewards preservation. But 'need' implies desire. And we have no idea how to make a computer program desire anything. React to outside stimuli - this can be emulated on a computer, but there is nothing with any sense of 'outside' and 'inside'. Others as necessary - see previous for problem with 'others'. Necessary is also problematic, because it implies desire or need?

If you can teach me how to make a computer program feel pain and pleasure, then I agree you can create ai that is sentient. If you can't, then no mater how interesting, complex, seemingly intelligent the code behaves, I don't see how you can consider it conscious.