I admit, I haven't delved too far into the EU after the OT. What you say about cloning himself for a thousand years is a reasonable point, but take into account that 1000 years is a very long time to play with your Empire and your imperial 'puppets' without anyone whom you could consider worthy of actually talking to and being kept company by. In the OT, Palpatine considered Vader to 'belong to him' (wouldn't any megalomaniac saturated in the Dark Side of the Force?), but at the same time, he referred to him as 'friend', and gave him great freedom and resources to pursue his own agenda (though only if Palpatine forsaw it to be of benefit to himself in the long-term of course!). Also, if I am correct, the Sith way requires the Apprentice to succeed his Master by taking his place (i.e. betraying and killing him). Therefore, if one of Palpatine's apprentices had ever in their lifetime been capable of defeating him despite his own great power and clairvoyance, I'm sure that in the Sith tradition, he would be satisfied that his 'replacement' was a worthy one, and that his role as Sith Lord was ultimately complete by grooming not a subordinate, not even an equal, but ultimately a superior. (He must have known that Vader would attempt to recruit Luke Skywalker as an ally in order to team up against and overthrow his rule, but he never intended to punish Vader for his treachery, particularly because he saw the potential for enlisting a healthier, uncrippled, stronger replacement for Vader, and believed himself to still ultimately be in control of Vader and the situation). If you are going to be killed in the end, then it might as well be at the hands of someone who shares your own religion and beliefs, is as capable as yourself, and will carry on your good work. So, although Palpatine made extensive plans for his infinite lifespan and indefinite rule of the Galaxy (he was nothing if not a prudent planner, we know this) through the cloning process, he would have quietly have expected his life to be ended prematurely by one of his superior pupils eventually, rather than by a Jedi, or a wretched Rebel insect! This is just my take of course!