4G won't be for use on phones for 2 more years at the earliest and it won't be practically viable for 3. It doesn't look like Verizon is going to worry about any intermediary systems like Wimax as Sprint did or HSPA+ like TMobile did (I think AT&T is still considering an HSPA+ system but as far as I know isn't committed to it yet). We would be on a Wimax system if we did go to an intermediary because it is a sort of expanded CDMA. I imagine that Verizon being fairly comfortable right now on top and not likely to fall too far in the next 2-3 years is pretty comfortable with having a good stable fast 3G network that covers more area than any one else and is going to spend most of their system upgrade money on pushing LTE out here as quickly as possible while everyone else wastes money on intermediary technologies that so far are proving somewhat lackluster.
All that being said no the Incredible will not be able to take advantage of LTE or even Wimax should they for some reason decide to go that route. 3G will be supported probably for atleast another 5 to 10 years after that as probably will 2G. Considering LTE is a considerably different technology I would wager probably more like 5 than 10 but it will depend on how long it will take for people to get rid of their older tech for newer. I know people with borderline antique cell phones still operating. One girl I know has a phone that can't send or recieve texts. I barely remember the last phone I had that couldn't do that or even when that was last an option. I felt like asking if she realized how often free phones were available.
So they will keep the system up for a while for late adopters but in all reality by the time you are replacing your incredible you probably still won't have an LTE option. According to the current official timeline LTE will be available for smartphones first around the end of 2012 and only in major cities. Late 2013 - Early 2014 for full blanketing. Expect slightly longer time than that because of equipment shortages, and unexpected pitfalls. We will all probably have at least one more phone on our new every 2 before whether or not it supports LTE is even a concern.
OK I take it back your next phone will probably be LTE. By the end of this year they expect to have LTE rolled out to major cities. The plan is by the end of this year to have modems running LTE on the network. By early 2012 they plan to have doubled their coverage and start rolling phones out and they will effectively blanket the country by 2013. So yeah hopefully your next smartphone will be LTE and we will be living it up. Probably by then X86 chips will be the norm maybe even AMD will get in on the game and we will have 2Ghz phones or so, possibly even multicore.
