Nah, Valve takes forever on releasing sequels to games that are fricking popular, Half-life and Counter-Strike. Obsidian takes for ever to release DLC. Games take longer to make then DLC, so Obsidian is worst. Though Valve do love to take their sweet ass time, [censored] IT I WANT HALF-LIFE EPISODE 3!!!!
And to answer the topics question, yes I am losing interest in the game, like every other game I have played, sooner or later, you will get bored of a game, shocking I know.
When they announced The Passing for L4D2 they said that around a month after it was released we could expect a DLC for L4D1.
We had to wait 6 months after it's release for The Sacrifice to be released...
And it's not like The Sacrifice was anything spectacular either, it had 2 new maps and one recycled one from The Passing and included a port of No Mercy.
So they took 6 months to release 2 new maps of a 3 map campaign.
They real slow.
At least the L4D team is anyway.
Probably sitting with their thumbs up their asses and sniffing glue.