Reiscool: this is a wrong way to start in many aspects, let me give you some advice about it:
> Title of the topic: You need to be more specific about what the set will be about. Something like "Future climate" or "Toyland > Future climate"
> poll: polls like this are absolutely pointless. It hasn't been the first one like this, at it's not a good presage that until now, none of the sets that have started with a "if I ever finish this set, would someone use it?" poll have ever been finished.
Think about it for a moment: you are doing this set because you like it, not because a lot of people
would use it if it's ever finished; don't you?
For that question, you don't need a poll; when you have a finished set, I can tell you that people
will download and try it. If they like it ot not, that's another business

But don't get lost in wondering what
would people in the future do if your set
was released.
Use polls to actually hear the opinion of people when you are doubting between some options (like "what colors do you like best for this traincar?", etc.)
> plan: you don't seem to have a plan. A specific plan, I mean. "replace toyland" is too vague, you need to plan first what are you going to replace, what kind of vehicles will appear, what will be the style for the graphics. In resume, you need a tracking table, to check what is already done and what is left, and with pictures of what it ould look like (since you don't have a real referent, pictures of futuristic designs)
> previous works: I think that there have been 2 projects for a toyland > future conversion, plus the existing one in George's site.
Well, to just ignore them and begin a whole new project on your own is not a good idea: because you have no plan. If you had a planned set with a fair tracking table and all your ideas put in order, then I could see it progressing. But as it is now, I have to tell you that it's doomed.
> sprites: you need to improve them, but keep drawing

you will progress if you hear advices from experienced artists.
Also, don't use JPG for the files: it deforms the image, PNG works better.
And I'm talking to you from my own experience: I have seen a lot of projects start the same way you have, and end forgotten in a matter of weeks.
I have started a project myself, the Spain set. The final version hasn't been released yet, so it has a lot of things to be fixed; but it's playable, and very near completion. These are the steps I walked in its creation:
> Before even thinking of start on my own; I worked first for another set. Indeed, you can't arrive and know what to do. I collaborated a lot of time in the Japan set, and eventually in other sets too, so I learned how things work in the process of developing a set.
> I asked for help of experienced members: mainly artists, coders and coordinators. They told me what would I basically need if I was going to start a new set.
> I prepared a tracking table, with information of Spanish locomotives, MUs and traincars. When it was done, krtaylor (who had coordinated the US and Japan sets previously) hosted it for me on his site.
And then, I created a thread in the forum: Spanish trains set. Off course, there was no poll asking if anyone would play with it if it was ever finished

I just invited anyone to join and lend me a hand. And they did. Some of the best artists form the forums came and collaborated with the set.
Eventually, when the set had advanced a lot, a coder named Death came and began releasing versions of the GRF.
> And thus, with a lot of planning and working together with a lot of people, the set has advanced a lot and is nearly done.