oh we need a lot of things unfortunately
there are a lot of good ideas here
1/ but the must have thing for our tyranids is giving to this army the rule "beasts" and "jump infantry" !!!!
"beasts" for lictors, warriors, hive guards, tyrants !, raveners, trygon, haruspex !, carnifex, toxicrene, rippers, OOE and swarmlord
"jump infantry" for shrikes, winged rippers, keep gargoyles, +/- horma
i noticed that we have MC with poor WS, poor initiative, poor save and overcosted, but tyranids are known as a close army and with don't have anything to go to close quickly...
I play also a necron army and i tabled my opponent yesterday on the 4th turn (against GK), with a decurion, 3 tomb blades, 1 annihilation barge, 5 wraiths, 1 canoptek spyder, 6 pretorian with a destroyer lord and lychgard
they have initiative 2 but have a good FNP and they move quickly, very very quickly, quicker than tyranid (you should cry if you see a judicator battalion)
and they have WS 4, F/T 4-5 and svg 3+ FNP 4-5+
i decided to test my tyranid army against the same list, and ... tyranid lost despite of 1 carnifex, 1 exocrine, 1 mawloc, 2 winged HT, 30 gaunt, 10 gargoyles, 6 warriors, 4 zoanthrope, 1 venom
so we need beasts to lock units or jump
2/ we need more WS and initiative, 4 minimum for or we need more biomorph like in the 4th and 5th to improve our MC
and decreasing drastically the cost of our MC...
it's a shame to see the cost of our MC :
carnifex 120
prime 120
tervigon : 200
trygon : 190 ..... (and doesn't worth it at all)
tyranofex : 175
exocrine 170
haruspex : 160....
if you see MC in other factions, it's always cheaper
3/ we need more punch !!! more weapons with AP 3 or 2 in melee or shooting and we need at least one D-weapons ...
more weapons to destroy vehicles, more options to deal with 13 or 14 armor
4/ IWND instead regeneration and cheaper......
and give EW or better, FNP 6+ or 5+ in the 12" of a synapse creature
5/ decrease the cost of stealer ! warriors, shrikes and ravelers, decrease the cost of bonesword, give AP2 to pair of bonesword
if we have this, i will love again my tyranid
6/ change the trygon in GC like before, or put hierodule, or dimachareon,
put malanthrope in the codex !