We'll get Java with a 1M installer, no more. It will runs some small programs, such as a telnet client and clones of ls, cat, more, ecc. utilities. When you will create a Java application, the new JVM will automatically download all missing libraries.
I don't believe Jigsaw will resurrect the Java desktop, but there's some scenarios we must reflect about. In these days Apple is trying to integrate its desktop with its mobile solution. The Mac App Store and the iPhone App Store are similar ideas; the Mac Book's trackpad is the same multitouch device of iPhone's display; Mobile Me's services work as a glue between your different Apple devices. In this "extremely dynamic scenario", informations (e-mails, photos, music, calendars, ecc.) are always in your hand. Why no expand this scenario to applications? Why no expand this scenario to your copy and scores of Angry Birds, or your copy and save games of Rage, they'll runs everywhere, downloading just the necessary informations from the network? It's true you can't have a Crysis written in Java, but a «Monkey Island Series» yes. This concept of «Buy Once, Run Everywhere» could potentially kill a set of market stores (where's the difference between a PS3 and a XBOX 360 and a WII if a donwloaded game runs everywhere?) and makes me doubtful about this prospective. But there's some players that could be interested on platform indipendence.
I introduce you an example: I buyed "Diablo 2" some years ago for PC. Blizzard gives me the opportunity to dowload a version for Mac OS X spending no money. They did a good work and I appreciate its honesty. Porting a game is an hard work, but in Java is trivial. Game's world is moving from power-players to casual-gamers and casual games don't need high performances or fancy graphics.
Java Jigsaw Platform could be a big opportunity some years ago. Now, with this commercial pressure oriented to kill every kind of portability, I am non very confident that Java will emerge from desktop sea.