Future solar missions
You're right SOHO could fail at anytime and I forgot about the STEREO mission to launch this spring.
Although launch won't occur until April 08 I'm looking forward to the Solar Dynamics Observatory (SDO) mission. It is the SOHO replacement to speak, with image data transmitted about every 15 seconds instead of SOHO's current 15 minutes.
SOHO has provided a lot of information for SDO and the geosynchronous orbit should allow for near continuos observation and data flow to earth.