Just looking down the toy aisles during the recent store resets I think there are a couple lines that could actually be both for kids and for collectors. But I also think there's a good number of lines out there that are really geared for kids only
Geared towards the kids, IMO, are lines like Avatar: The Last Airbender, Ben 10, Attacktix (SW, Marvel and Transformers), Sigma 6, Superman, The Batman, Power Rangers and TMNT. There are a couple other lines out that I can't recall names for right now that I also think are for kids rather than collectors, especially anything tied into a Saturday morning cartoon.
Collector oriented lines; Marvel Legends, Icons, Signature Series, and 3.75" Titanium figures. The DC line of 7-8" figures which I can't recall the name of falls into a collector line as well. The military vehicles from 21st in 1:18 scale are intended mainly for collectors.
Lines that have crossover appeal include Star Wars, Pirates of the Caribbean, Justice League, Spider-man, Transformers, Hot Wheels and Lego.
Within the SW line the basic figures and vehicles are crossover items as are the Titanium vehicles. The VOTC/VTSC and 3.75" Titanium figures are collector targeted items while Unleashed Battle Packs, Transformers, Galactic Heroes and role play items are aimed more at kids. Star Wars, though, is one of the few properties where collectors will buy it all, even stuff not aimed at them like Galactic Heroes.
The Spider-man line is a mixed bag with most of the SM figures aimed at kids while some of the villains are Marvel Legends quality and have crossover appeal. Justice League is the same way, you have Batman and Superman which the kids love but then you have some of the 3-packs with odd characters that collectors love to buy.
POTC, I would have thought, was a kids line but people on this board have proven that it has collector appeal. And I can understand that because while I listed Ben 10 as a kids line I was very tempted to collect the 4" line of figures and accessories in that scale. Both Ben 10 and POTC have the potential for wider appeal. I wonder if anyone collects Ben 10 though?
Transformers have both kid and collector oriented offerings but just like Star Wars, collectors buy it all, they don't stick to just what's put out with them in mind.
I'm not sure where McFarlane falls anymore but I'd say their main target is collectors. Hot Wheels and the like are intended for both but Hot Wheels, at least, caters to collectors with their Treasure Hunt vehicles.
While I think Lego was originally intended for kids, and still is, it's a very collectible product. I think Lego recognizes that with their Ultimate Collector Series items but while their prices get kind of high some times, they are a kid-friendly company.
I guess, ultimately, anything could be collectible these days. As I said earlier, I was really temped to buy the Ben 10 line just because I loved the look and style of the figures and the quality. The line has very colorful and attractive packaging and I just think it looks cool.