I love the people who claim "tape is dead" but have not used the most recent high end tape solutions.
Right now LTO3 is probably the biggest standard. LTO3 allows for 400GB of uncompressed data to be stored n a $75.00 tape cartridge. Performance is 60MB/s sustained read/write. The biggest problem is having a disk subsystem that can sustain that level of throughput to keep the tape drives from wind-milling. This is typically accomplished by deep buffers on the tape drives themselves. We routinely see 100MB/s performance to LTO3 on typical user shares where we get about 1.6X compression.
LTO4 is due out soon, which will double the above to 800Gb uncompressed and 120MB/s read/write performance. Cartridges will be about $120 initially but will come down with time.
Quantum has SDLT600 which is similar in performance and capacity.
Sony has AIT and SAIT which are also competitive in performance and capacity.
So, with this said, we have 3 high end tape formats that are all alive and prospering. This certainly doesn't sound like "tape is dead" to me....
Yeah, that helps to keep things in perspective. I think what you're saying is that we're just seeing a new layer being added into the storage hierarchy, but the old layers won't necessarily go away. Though I think in many deployments, they will. A lot of people just backup HDDs by dup'ing them onto other HDDs now, forgoing tape or optical media. But there's probably still many more data centers still using tape.
Personally I haven't used any tape drives for backup since the SCSI Exabytes about 12 years ago, and don't see any reason to look in that direction. I played with backing up my stuff onto miniDV tapes using firewire, but it's too slow, and DV tapes are too unreliable, you need to use an awful lot of redundancy to safely write a backup, which eats into the overall capacity. So anyway, I believe in due time the bottom (old/slow) layers of the storage hierarchy will vanish.