I must agree with many people posting here, after looking at a lot of screens out there, there is very little reason to worry about 1080P unless you are going to a 58" or bigger screen.
When viewing 50" screen a scientific test developed by the BBC shows that people can't see the difference between 720P and 1080P unless you are 6.5" or less from the screen, a distance almost no one would sit from a 50" screen. See the BBC data at:
For up-converting there is especially no reason to go to 1080P vs 720P, since the video processor has to interpolate the picture into something it isn't. It is actually more complex to interpolate to higher resolutions, and more likely for the results to be worse rather than better (especially on cheaper players).
Most people will notice right away that the contrast ratio of the picture takes a hit with higher resolutions, causing the 720P screens to be brighter with more "POP" in the picture in most cases. This is due to the fact it is easier to make fewer larger pixels bright, rather than many small pixels. The history of the Panasonic screens makes this obvious (one easy example of many is the older Panasonic Pro models for example, the 720P TH42PHD8UK was 3000:1 but the 480P TH42PHD8UK was 4000:1. The newer ones follow the same rule, the 720P TH50PX75U is 10000:1 vs the 1080P TH50PZ700U is 5000:1, half the contrast ratio). This actually makes the PX75U screen look a lot better when comparing them side by side from 7 feet or more. The rule of thumb recommendation I have found pretty accurate is optimal viewing distance from the screen should be 2x screen size. So for a 50" screen you should be close to 8 feet away.
The chances for 1080P broadcast/cable/sat channels is slim due to the immense bandwidth requirements needed. To move a single channel from 1080i to 1080P requires twice the bandwidth since you are going from 30fps to 60fps (as in 1920x1080x60 vs 1920x1080x30). I wouldn't hold my breath until you get a fiber cable into your house, which is far away for most of us. Due to the frame rate on the 1080i being half the frame rate on the 720P, you will see more motion related issues on the 1080i, especially on fast moving scenes and sports.
As for other screen types mentioned here. There are several downsides people forget about. The LCOS and DLP screens all have expensive lamps cooled with noisy fans. Lamp life is from 4-8k hours. Average lamp life of 6k hours (on the optimistic side) means if you compare them to Panasonic Plasma rated half life of 60k hours (LCD's are about the same), you will be buying 10 DLP or LCOS lamps over the lifetime of the set. With many of the lamps costing close to $300 each, you will be spending close to $3k on lamps alone. You can buy 2 Panasonic 50" plasma screens for little more than that. All RP TV's are going the way of the DoDo, being relegated to the biggest screen sizes now and are going to disappear completely in a couple of years as the LCD's and Plasma's price drops and they become cost competitive at the bigger sizes. You can already see the trend, DLP's used to be around 46", then 52", 60" and bigger. As the LCD's an Plasma become affordable at those sizes, you will notice the RP's disappering rapidly up the ladder.
Many of the newer LCD's have shiny plastic screens, (similar to the Brightview laptop screens) causing similar or identical reflections in bright rooms. Considering that Panasonic offers the excellent anti-reflective PX77U, I would be something I would look closely at before considering LCD's.
The bottom line I guess I am getting at is that anyone worrying about future proofing themselves 10 years into the future is fooling themselves. There is always going to be something bigger and better around the corner, and it is easier to upgrade from a $1500 screen couple of years from now rather than swallow the $4k screen.
I found this out the hard way when I bought my SD Sony 36" XBR flat CRT in 2000 for over $2000. Replaced it with my Panasonic Pro 42" in 2006 for $1200, and will probably replace that with something bigger in a couple of years for $?????
So the bottom line, enjoy the 50" 720P now, when 1080P finally takes off years from now, you'll be able to buy a 65" 1080P Plasma for about $1k. As a reminder of how things are progressing, count how many HD channels you have now, and how many are more than 720P. Last time I checked, I had about 18 HD channels vs about 300 SD channels. Last time I checked Blockbuster, they had a few thousand SD movies and about 100HD movies. You can get SD movies for about $15, HD movies are 2 to 3 times that. I think we have a long way to go before worrying about 1080P compatibility.
One last hint to many out there. Set your source output to match the screen you are using. Don't have your cable box take a 480i channel, up convert it to 1080i and then have your screen down covert it to 720P (or 480P etc. etc). Same with your up-converting DVD player. Don't convert a SD DVD from 480i to 720P just to have your screen re-convert it to higher or lower resolution. I noticed motion problems (hesitation, judder, etc) on many screens due to the double conversion. If your screen is 720P, set your cable box, SAT or up-converting DVD outputs to 720P, if your screen is 1080P set everything you have to 1080P as much as possible. It will make your video much smoother in many cases, as I found out first hand on my Plasma screen.