I don't think the AV companies will bother too much as long as Microsoft don't try to force it as an update, offer unlimited free licenses to commercial users or include it on the Windows disk. After all Live Onecare didn't exactly set the market alight or they wouldn't have had to discontinue it.
Morro may affect the main players in the freebie market, but I suppose we'll have to have a look at it first. Rumour suggests it's to be "No frills" this could be good as in no Bloatware and low footprint, or bad as in too few features. I'll be checking it out when it appears.